2008-05-12 19:20:42 +00:00
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#
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2008-10-06 23:06:12 +00:00
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# Architectures that offer an FUNCTION_TRACER implementation should
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# select HAVE_FUNCTION_TRACER:
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2008-05-12 19:20:42 +00:00
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#
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2008-09-21 18:12:14 +00:00
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2008-11-23 10:39:08 +00:00
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config USER_STACKTRACE_SUPPORT
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bool
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2008-09-21 18:12:14 +00:00
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config NOP_TRACER
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bool
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ring-buffer: add NMI protection for spinlocks
Impact: prevent deadlock in NMI
The ring buffers are not yet totally lockless with writing to
the buffer. When a writer crosses a page, it grabs a per cpu spinlock
to protect against a reader. The spinlocks taken by a writer are not
to protect against other writers, since a writer can only write to
its own per cpu buffer. The spinlocks protect against readers that
can touch any cpu buffer. The writers are made to be reentrant
with the spinlocks disabling interrupts.
The problem arises when an NMI writes to the buffer, and that write
crosses a page boundary. If it grabs a spinlock, it can be racing
with another writer (since disabling interrupts does not protect
against NMIs) or with a reader on the same CPU. Luckily, most of the
users are not reentrant and protects against this issue. But if a
user of the ring buffer becomes reentrant (which is what the ring
buffers do allow), if the NMI also writes to the ring buffer then
we risk the chance of a deadlock.
This patch moves the ftrace_nmi_enter called by nmi_enter() to the
ring buffer code. It replaces the current ftrace_nmi_enter that is
used by arch specific code to arch_ftrace_nmi_enter and updates
the Kconfig to handle it.
When an NMI is called, it will set a per cpu variable in the ring buffer
code and will clear it when the NMI exits. If a write to the ring buffer
crosses page boundaries inside an NMI, a trylock is used on the spin
lock instead. If the spinlock fails to be acquired, then the entry
is discarded.
This bug appeared in the ftrace work in the RT tree, where event tracing
is reentrant. This workaround solved the deadlocks that appeared there.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-05 23:43:07 +00:00
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config HAVE_FTRACE_NMI_ENTER
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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ring-buffer: add NMI protection for spinlocks
Impact: prevent deadlock in NMI
The ring buffers are not yet totally lockless with writing to
the buffer. When a writer crosses a page, it grabs a per cpu spinlock
to protect against a reader. The spinlocks taken by a writer are not
to protect against other writers, since a writer can only write to
its own per cpu buffer. The spinlocks protect against readers that
can touch any cpu buffer. The writers are made to be reentrant
with the spinlocks disabling interrupts.
The problem arises when an NMI writes to the buffer, and that write
crosses a page boundary. If it grabs a spinlock, it can be racing
with another writer (since disabling interrupts does not protect
against NMIs) or with a reader on the same CPU. Luckily, most of the
users are not reentrant and protects against this issue. But if a
user of the ring buffer becomes reentrant (which is what the ring
buffers do allow), if the NMI also writes to the ring buffer then
we risk the chance of a deadlock.
This patch moves the ftrace_nmi_enter called by nmi_enter() to the
ring buffer code. It replaces the current ftrace_nmi_enter that is
used by arch specific code to arch_ftrace_nmi_enter and updates
the Kconfig to handle it.
When an NMI is called, it will set a per cpu variable in the ring buffer
code and will clear it when the NMI exits. If a write to the ring buffer
crosses page boundaries inside an NMI, a trylock is used on the spin
lock instead. If the spinlock fails to be acquired, then the entry
is discarded.
This bug appeared in the ftrace work in the RT tree, where event tracing
is reentrant. This workaround solved the deadlocks that appeared there.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-05 23:43:07 +00:00
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2008-10-06 23:06:12 +00:00
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config HAVE_FUNCTION_TRACER
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2008-05-12 19:20:42 +00:00
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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2008-05-12 19:20:42 +00:00
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2008-11-25 20:07:04 +00:00
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config HAVE_FUNCTION_GRAPH_TRACER
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2008-11-11 06:14:25 +00:00
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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2008-11-11 06:14:25 +00:00
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function-graph: add stack frame test
In case gcc does something funny with the stack frames, or the return
from function code, we would like to detect that.
An arch may implement passing of a variable that is unique to the
function and can be saved on entering a function and can be tested
when exiting the function. Usually the frame pointer can be used for
this purpose.
This patch also implements this for x86. Where it passes in the stack
frame of the parent function, and will test that frame on exit.
There was a case in x86_32 with optimize for size (-Os) where, for a
few functions, gcc would align the stack frame and place a copy of the
return address into it. The function graph tracer modified the copy and
not the actual return address. On return from the funtion, it did not go
to the tracer hook, but returned to the parent. This broke the function
graph tracer, because the return of the parent (where gcc did not do
this funky manipulation) returned to the location that the child function
was suppose to. This caused strange kernel crashes.
This test detected the problem and pointed out where the issue was.
This modifies the parameters of one of the functions that the arch
specific code calls, so it includes changes to arch code to accommodate
the new prototype.
Note, I notice that the parsic arch implements its own push_return_trace.
This is now a generic function and the ftrace_push_return_trace should be
used instead. This patch does not touch that code.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-18 16:45:08 +00:00
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config HAVE_FUNCTION_GRAPH_FP_TEST
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bool
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help
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An arch may pass in a unique value (frame pointer) to both the
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entering and exiting of a function. On exit, the value is compared
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and if it does not match, then it will panic the kernel.
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2008-11-05 21:05:44 +00:00
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config HAVE_FUNCTION_TRACE_MCOUNT_TEST
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bool
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help
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2009-09-15 00:10:15 +00:00
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See Documentation/trace/ftrace-implementation.txt
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2008-11-05 21:05:44 +00:00
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2008-05-17 04:01:36 +00:00
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config HAVE_DYNAMIC_FTRACE
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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2008-05-17 04:01:36 +00:00
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ftrace: create __mcount_loc section
This patch creates a section in the kernel called "__mcount_loc".
This will hold a list of pointers to the mcount relocation for
each call site of mcount.
For example:
objdump -dr init/main.o
[...]
Disassembly of section .text:
0000000000000000 <do_one_initcall>:
0: 55 push %rbp
[...]
000000000000017b <init_post>:
17b: 55 push %rbp
17c: 48 89 e5 mov %rsp,%rbp
17f: 53 push %rbx
180: 48 83 ec 08 sub $0x8,%rsp
184: e8 00 00 00 00 callq 189 <init_post+0xe>
185: R_X86_64_PC32 mcount+0xfffffffffffffffc
[...]
We will add a section to point to each function call.
.section __mcount_loc,"a",@progbits
[...]
.quad .text + 0x185
[...]
The offset to of the mcount call site in init_post is an offset from
the start of the section, and not the start of the function init_post.
The mcount relocation is at the call site 0x185 from the start of the
.text section.
.text + 0x185 == init_post + 0xa
We need a way to add this __mcount_loc section in a way that we do not
lose the relocations after final link. The .text section here will
be attached to all other .text sections after final link and the
offsets will be meaningless. We need to keep track of where these
.text sections are.
To do this, we use the start of the first function in the section.
do_one_initcall. We can make a tmp.s file with this function as a reference
to the start of the .text section.
.section __mcount_loc,"a",@progbits
[...]
.quad do_one_initcall + 0x185
[...]
Then we can compile the tmp.s into a tmp.o
gcc -c tmp.s -o tmp.o
And link it into back into main.o.
ld -r main.o tmp.o -o tmp_main.o
mv tmp_main.o main.o
But we have a problem. What happens if the first function in a section
is not exported, and is a static function. The linker will not let
the tmp.o use it. This case exists in main.o as well.
Disassembly of section .init.text:
0000000000000000 <set_reset_devices>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: e8 00 00 00 00 callq 9 <set_reset_devices+0x9>
5: R_X86_64_PC32 mcount+0xfffffffffffffffc
The first function in .init.text is a static function.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
The lowercase 't' means that set_reset_devices is local and is not exported.
If we simply try to link the tmp.o with the set_reset_devices we end
up with two symbols: one local and one global.
.section __mcount_loc,"a",@progbits
.quad set_reset_devices + 0x10
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
U set_reset_devices
We still have an undefined reference to set_reset_devices, and if we try
to compile the kernel, we will end up with an undefined reference to
set_reset_devices, or even worst, it could be exported someplace else,
and then we will have a reference to the wrong location.
To handle this case, we make an intermediate step using objcopy.
We convert set_reset_devices into a global exported symbol before linking
it with tmp.o and set it back afterwards.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
Now we have a section in main.o called __mcount_loc that we can place
somewhere in the kernel using vmlinux.ld.S and access it to convert
all these locations that call mcount into nops before starting SMP
and thus, eliminating the need to do this with kstop_machine.
Note, A well documented perl script (scripts/recordmcount.pl) is used
to do all this in one location.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 19:45:07 +00:00
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config HAVE_FTRACE_MCOUNT_RECORD
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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ftrace: create __mcount_loc section
This patch creates a section in the kernel called "__mcount_loc".
This will hold a list of pointers to the mcount relocation for
each call site of mcount.
For example:
objdump -dr init/main.o
[...]
Disassembly of section .text:
0000000000000000 <do_one_initcall>:
0: 55 push %rbp
[...]
000000000000017b <init_post>:
17b: 55 push %rbp
17c: 48 89 e5 mov %rsp,%rbp
17f: 53 push %rbx
180: 48 83 ec 08 sub $0x8,%rsp
184: e8 00 00 00 00 callq 189 <init_post+0xe>
185: R_X86_64_PC32 mcount+0xfffffffffffffffc
[...]
We will add a section to point to each function call.
.section __mcount_loc,"a",@progbits
[...]
.quad .text + 0x185
[...]
The offset to of the mcount call site in init_post is an offset from
the start of the section, and not the start of the function init_post.
The mcount relocation is at the call site 0x185 from the start of the
.text section.
.text + 0x185 == init_post + 0xa
We need a way to add this __mcount_loc section in a way that we do not
lose the relocations after final link. The .text section here will
be attached to all other .text sections after final link and the
offsets will be meaningless. We need to keep track of where these
.text sections are.
To do this, we use the start of the first function in the section.
do_one_initcall. We can make a tmp.s file with this function as a reference
to the start of the .text section.
.section __mcount_loc,"a",@progbits
[...]
.quad do_one_initcall + 0x185
[...]
Then we can compile the tmp.s into a tmp.o
gcc -c tmp.s -o tmp.o
And link it into back into main.o.
ld -r main.o tmp.o -o tmp_main.o
mv tmp_main.o main.o
But we have a problem. What happens if the first function in a section
is not exported, and is a static function. The linker will not let
the tmp.o use it. This case exists in main.o as well.
Disassembly of section .init.text:
0000000000000000 <set_reset_devices>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: e8 00 00 00 00 callq 9 <set_reset_devices+0x9>
5: R_X86_64_PC32 mcount+0xfffffffffffffffc
The first function in .init.text is a static function.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
The lowercase 't' means that set_reset_devices is local and is not exported.
If we simply try to link the tmp.o with the set_reset_devices we end
up with two symbols: one local and one global.
.section __mcount_loc,"a",@progbits
.quad set_reset_devices + 0x10
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
U set_reset_devices
We still have an undefined reference to set_reset_devices, and if we try
to compile the kernel, we will end up with an undefined reference to
set_reset_devices, or even worst, it could be exported someplace else,
and then we will have a reference to the wrong location.
To handle this case, we make an intermediate step using objcopy.
We convert set_reset_devices into a global exported symbol before linking
it with tmp.o and set it back afterwards.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
Now we have a section in main.o called __mcount_loc that we can place
somewhere in the kernel using vmlinux.ld.S and access it to convert
all these locations that call mcount into nops before starting SMP
and thus, eliminating the need to do this with kstop_machine.
Note, A well documented perl script (scripts/recordmcount.pl) is used
to do all this in one location.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 19:45:07 +00:00
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2008-11-25 08:24:15 +00:00
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config HAVE_HW_BRANCH_TRACER
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bool
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2009-08-24 21:43:11 +00:00
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config HAVE_SYSCALL_TRACEPOINTS
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2009-03-07 04:52:59 +00:00
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bool
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2009-09-15 00:10:15 +00:00
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help
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See Documentation/trace/ftrace-implementation.txt
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2009-03-07 04:52:59 +00:00
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2008-05-12 19:20:42 +00:00
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config TRACER_MAX_TRACE
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bool
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tracing: unified trace buffer
This is a unified tracing buffer that implements a ring buffer that
hopefully everyone will eventually be able to use.
The events recorded into the buffer have the following structure:
struct ring_buffer_event {
u32 type:2, len:3, time_delta:27;
u32 array[];
};
The minimum size of an event is 8 bytes. All events are 4 byte
aligned inside the buffer.
There are 4 types (all internal use for the ring buffer, only
the data type is exported to the interface users).
RINGBUF_TYPE_PADDING: this type is used to note extra space at the end
of a buffer page.
RINGBUF_TYPE_TIME_EXTENT: This type is used when the time between events
is greater than the 27 bit delta can hold. We add another
32 bits, and record that in its own event (8 byte size).
RINGBUF_TYPE_TIME_STAMP: (Not implemented yet). This will hold data to
help keep the buffer timestamps in sync.
RINGBUF_TYPE_DATA: The event actually holds user data.
The "len" field is only three bits. Since the data must be
4 byte aligned, this field is shifted left by 2, giving a
max length of 28 bytes. If the data load is greater than 28
bytes, the first array field holds the full length of the
data load and the len field is set to zero.
Example, data size of 7 bytes:
type = RINGBUF_TYPE_DATA
len = 2
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0..1]: <7 bytes of data> <1 byte empty>
This event is saved in 12 bytes of the buffer.
An event with 82 bytes of data:
type = RINGBUF_TYPE_DATA
len = 0
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0]: 84 (Note the alignment)
array[1..14]: <82 bytes of data> <2 bytes empty>
The above event is saved in 92 bytes (if my math is correct).
82 bytes of data, 2 bytes empty, 4 byte header, 4 byte length.
Do not reference the above event struct directly. Use the following
functions to gain access to the event table, since the
ring_buffer_event structure may change in the future.
ring_buffer_event_length(event): get the length of the event.
This is the size of the memory used to record this
event, and not the size of the data pay load.
ring_buffer_time_delta(event): get the time delta of the event
This returns the delta time stamp since the last event.
Note: Even though this is in the header, there should
be no reason to access this directly, accept
for debugging.
ring_buffer_event_data(event): get the data from the event
This is the function to use to get the actual data
from the event. Note, it is only a pointer to the
data inside the buffer. This data must be copied to
another location otherwise you risk it being written
over in the buffer.
ring_buffer_lock: A way to lock the entire buffer.
ring_buffer_unlock: unlock the buffer.
ring_buffer_alloc: create a new ring buffer. Can choose between
overwrite or consumer/producer mode. Overwrite will
overwrite old data, where as consumer producer will
throw away new data if the consumer catches up with the
producer. The consumer/producer is the default.
ring_buffer_free: free the ring buffer.
ring_buffer_resize: resize the buffer. Changes the size of each cpu
buffer. Note, it is up to the caller to provide that
the buffer is not being used while this is happening.
This requirement may go away but do not count on it.
ring_buffer_lock_reserve: locks the ring buffer and allocates an
entry on the buffer to write to.
ring_buffer_unlock_commit: unlocks the ring buffer and commits it to
the buffer.
ring_buffer_write: writes some data into the ring buffer.
ring_buffer_peek: Look at a next item in the cpu buffer.
ring_buffer_consume: get the next item in the cpu buffer and
consume it. That is, this function increments the head
pointer.
ring_buffer_read_start: Start an iterator of a cpu buffer.
For now, this disables the cpu buffer, until you issue
a finish. This is just because we do not want the iterator
to be overwritten. This restriction may change in the future.
But note, this is used for static reading of a buffer which
is usually done "after" a trace. Live readings would want
to use the ring_buffer_consume above, which will not
disable the ring buffer.
ring_buffer_read_finish: Finishes the read iterator and reenables
the ring buffer.
ring_buffer_iter_peek: Look at the next item in the cpu iterator.
ring_buffer_read: Read the iterator and increment it.
ring_buffer_iter_reset: Reset the iterator to point to the beginning
of the cpu buffer.
ring_buffer_iter_empty: Returns true if the iterator is at the end
of the cpu buffer.
ring_buffer_size: returns the size in bytes of each cpu buffer.
Note, the real size is this times the number of CPUs.
ring_buffer_reset_cpu: Sets the cpu buffer to empty
ring_buffer_reset: sets all cpu buffers to empty
ring_buffer_swap_cpu: swaps a cpu buffer from one buffer with a
cpu buffer of another buffer. This is handy when you
want to take a snap shot of a running trace on just one
cpu. Having a backup buffer, to swap with facilitates this.
Ftrace max latencies use this.
ring_buffer_empty: Returns true if the ring buffer is empty.
ring_buffer_empty_cpu: Returns true if the cpu buffer is empty.
ring_buffer_record_disable: disable all cpu buffers (read only)
ring_buffer_record_disable_cpu: disable a single cpu buffer (read only)
ring_buffer_record_enable: enable all cpu buffers.
ring_buffer_record_enabl_cpu: enable a single cpu buffer.
ring_buffer_entries: The number of entries in a ring buffer.
ring_buffer_overruns: The number of entries removed due to writing wrap.
ring_buffer_time_stamp: Get the time stamp used by the ring buffer
ring_buffer_normalize_time_stamp: normalize the ring buffer time stamp
into nanosecs.
I still need to implement the GTOD feature. But we need support from
the cpu frequency infrastructure. But this can be done at a later
time without affecting the ring buffer interface.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-30 03:02:38 +00:00
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config RING_BUFFER
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bool
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ring-buffer: add NMI protection for spinlocks
Impact: prevent deadlock in NMI
The ring buffers are not yet totally lockless with writing to
the buffer. When a writer crosses a page, it grabs a per cpu spinlock
to protect against a reader. The spinlocks taken by a writer are not
to protect against other writers, since a writer can only write to
its own per cpu buffer. The spinlocks protect against readers that
can touch any cpu buffer. The writers are made to be reentrant
with the spinlocks disabling interrupts.
The problem arises when an NMI writes to the buffer, and that write
crosses a page boundary. If it grabs a spinlock, it can be racing
with another writer (since disabling interrupts does not protect
against NMIs) or with a reader on the same CPU. Luckily, most of the
users are not reentrant and protects against this issue. But if a
user of the ring buffer becomes reentrant (which is what the ring
buffers do allow), if the NMI also writes to the ring buffer then
we risk the chance of a deadlock.
This patch moves the ftrace_nmi_enter called by nmi_enter() to the
ring buffer code. It replaces the current ftrace_nmi_enter that is
used by arch specific code to arch_ftrace_nmi_enter and updates
the Kconfig to handle it.
When an NMI is called, it will set a per cpu variable in the ring buffer
code and will clear it when the NMI exits. If a write to the ring buffer
crosses page boundaries inside an NMI, a trylock is used on the spin
lock instead. If the spinlock fails to be acquired, then the entry
is discarded.
This bug appeared in the ftrace work in the RT tree, where event tracing
is reentrant. This workaround solved the deadlocks that appeared there.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-05 23:43:07 +00:00
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config FTRACE_NMI_ENTER
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bool
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depends on HAVE_FTRACE_NMI_ENTER
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default y
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2009-04-08 08:14:01 +00:00
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config EVENT_TRACING
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2009-05-25 10:11:59 +00:00
|
|
|
select CONTEXT_SWITCH_TRACER
|
|
|
|
|
bool
|
|
|
|
|
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|
|
|
|
config CONTEXT_SWITCH_TRACER
|
2009-04-08 08:14:01 +00:00
|
|
|
bool
|
|
|
|
|
|
2009-09-04 18:24:40 +00:00
|
|
|
config RING_BUFFER_ALLOW_SWAP
|
|
|
|
|
bool
|
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|
|
|
help
|
|
|
|
|
Allow the use of ring_buffer_swap_cpu.
|
|
|
|
|
Adds a very slight overhead to tracing when enabled.
|
|
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|
|
|
2009-05-28 19:50:13 +00:00
|
|
|
# All tracer options should select GENERIC_TRACER. For those options that are
|
|
|
|
|
# enabled by all tracers (context switch and event tracer) they select TRACING.
|
|
|
|
|
# This allows those options to appear when no other tracer is selected. But the
|
|
|
|
|
# options do not appear when something else selects it. We need the two options
|
|
|
|
|
# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
|
2009-08-05 20:06:42 +00:00
|
|
|
# hidding of the automatic options.
|
2009-05-28 19:50:13 +00:00
|
|
|
|
2008-05-12 19:20:42 +00:00
|
|
|
config TRACING
|
|
|
|
|
bool
|
|
|
|
|
select DEBUG_FS
|
tracing: unified trace buffer
This is a unified tracing buffer that implements a ring buffer that
hopefully everyone will eventually be able to use.
The events recorded into the buffer have the following structure:
struct ring_buffer_event {
u32 type:2, len:3, time_delta:27;
u32 array[];
};
The minimum size of an event is 8 bytes. All events are 4 byte
aligned inside the buffer.
There are 4 types (all internal use for the ring buffer, only
the data type is exported to the interface users).
RINGBUF_TYPE_PADDING: this type is used to note extra space at the end
of a buffer page.
RINGBUF_TYPE_TIME_EXTENT: This type is used when the time between events
is greater than the 27 bit delta can hold. We add another
32 bits, and record that in its own event (8 byte size).
RINGBUF_TYPE_TIME_STAMP: (Not implemented yet). This will hold data to
help keep the buffer timestamps in sync.
RINGBUF_TYPE_DATA: The event actually holds user data.
The "len" field is only three bits. Since the data must be
4 byte aligned, this field is shifted left by 2, giving a
max length of 28 bytes. If the data load is greater than 28
bytes, the first array field holds the full length of the
data load and the len field is set to zero.
Example, data size of 7 bytes:
type = RINGBUF_TYPE_DATA
len = 2
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0..1]: <7 bytes of data> <1 byte empty>
This event is saved in 12 bytes of the buffer.
An event with 82 bytes of data:
type = RINGBUF_TYPE_DATA
len = 0
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0]: 84 (Note the alignment)
array[1..14]: <82 bytes of data> <2 bytes empty>
The above event is saved in 92 bytes (if my math is correct).
82 bytes of data, 2 bytes empty, 4 byte header, 4 byte length.
Do not reference the above event struct directly. Use the following
functions to gain access to the event table, since the
ring_buffer_event structure may change in the future.
ring_buffer_event_length(event): get the length of the event.
This is the size of the memory used to record this
event, and not the size of the data pay load.
ring_buffer_time_delta(event): get the time delta of the event
This returns the delta time stamp since the last event.
Note: Even though this is in the header, there should
be no reason to access this directly, accept
for debugging.
ring_buffer_event_data(event): get the data from the event
This is the function to use to get the actual data
from the event. Note, it is only a pointer to the
data inside the buffer. This data must be copied to
another location otherwise you risk it being written
over in the buffer.
ring_buffer_lock: A way to lock the entire buffer.
ring_buffer_unlock: unlock the buffer.
ring_buffer_alloc: create a new ring buffer. Can choose between
overwrite or consumer/producer mode. Overwrite will
overwrite old data, where as consumer producer will
throw away new data if the consumer catches up with the
producer. The consumer/producer is the default.
ring_buffer_free: free the ring buffer.
ring_buffer_resize: resize the buffer. Changes the size of each cpu
buffer. Note, it is up to the caller to provide that
the buffer is not being used while this is happening.
This requirement may go away but do not count on it.
ring_buffer_lock_reserve: locks the ring buffer and allocates an
entry on the buffer to write to.
ring_buffer_unlock_commit: unlocks the ring buffer and commits it to
the buffer.
ring_buffer_write: writes some data into the ring buffer.
ring_buffer_peek: Look at a next item in the cpu buffer.
ring_buffer_consume: get the next item in the cpu buffer and
consume it. That is, this function increments the head
pointer.
ring_buffer_read_start: Start an iterator of a cpu buffer.
For now, this disables the cpu buffer, until you issue
a finish. This is just because we do not want the iterator
to be overwritten. This restriction may change in the future.
But note, this is used for static reading of a buffer which
is usually done "after" a trace. Live readings would want
to use the ring_buffer_consume above, which will not
disable the ring buffer.
ring_buffer_read_finish: Finishes the read iterator and reenables
the ring buffer.
ring_buffer_iter_peek: Look at the next item in the cpu iterator.
ring_buffer_read: Read the iterator and increment it.
ring_buffer_iter_reset: Reset the iterator to point to the beginning
of the cpu buffer.
ring_buffer_iter_empty: Returns true if the iterator is at the end
of the cpu buffer.
ring_buffer_size: returns the size in bytes of each cpu buffer.
Note, the real size is this times the number of CPUs.
ring_buffer_reset_cpu: Sets the cpu buffer to empty
ring_buffer_reset: sets all cpu buffers to empty
ring_buffer_swap_cpu: swaps a cpu buffer from one buffer with a
cpu buffer of another buffer. This is handy when you
want to take a snap shot of a running trace on just one
cpu. Having a backup buffer, to swap with facilitates this.
Ftrace max latencies use this.
ring_buffer_empty: Returns true if the ring buffer is empty.
ring_buffer_empty_cpu: Returns true if the cpu buffer is empty.
ring_buffer_record_disable: disable all cpu buffers (read only)
ring_buffer_record_disable_cpu: disable a single cpu buffer (read only)
ring_buffer_record_enable: enable all cpu buffers.
ring_buffer_record_enabl_cpu: enable a single cpu buffer.
ring_buffer_entries: The number of entries in a ring buffer.
ring_buffer_overruns: The number of entries removed due to writing wrap.
ring_buffer_time_stamp: Get the time stamp used by the ring buffer
ring_buffer_normalize_time_stamp: normalize the ring buffer time stamp
into nanosecs.
I still need to implement the GTOD feature. But we need support from
the cpu frequency infrastructure. But this can be done at a later
time without affecting the ring buffer interface.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-30 03:02:38 +00:00
|
|
|
select RING_BUFFER
|
2008-10-31 19:50:41 +00:00
|
|
|
select STACKTRACE if STACKTRACE_SUPPORT
|
2008-07-23 12:15:22 +00:00
|
|
|
select TRACEPOINTS
|
2008-10-29 15:15:57 +00:00
|
|
|
select NOP_TRACER
|
2009-03-06 16:21:49 +00:00
|
|
|
select BINARY_PRINTF
|
2009-04-08 08:14:01 +00:00
|
|
|
select EVENT_TRACING
|
2008-05-12 19:20:42 +00:00
|
|
|
|
2009-05-28 19:50:13 +00:00
|
|
|
config GENERIC_TRACER
|
|
|
|
|
bool
|
|
|
|
|
select TRACING
|
|
|
|
|
|
2009-03-05 20:19:55 +00:00
|
|
|
#
|
|
|
|
|
# Minimum requirements an architecture has to meet for us to
|
|
|
|
|
# be able to offer generic tracing facilities:
|
|
|
|
|
#
|
|
|
|
|
config TRACING_SUPPORT
|
|
|
|
|
bool
|
2009-03-23 22:07:24 +00:00
|
|
|
# PPC32 has no irqflags tracing support, but it can use most of the
|
|
|
|
|
# tracers anyway, they were tested to build and work. Note that new
|
|
|
|
|
# exceptions to this list aren't welcomed, better implement the
|
|
|
|
|
# irqflags tracing for your architecture.
|
|
|
|
|
depends on TRACE_IRQFLAGS_SUPPORT || PPC32
|
2009-03-05 20:19:55 +00:00
|
|
|
depends on STACKTRACE_SUPPORT
|
2009-03-06 01:40:53 +00:00
|
|
|
default y
|
2009-03-05 20:19:55 +00:00
|
|
|
|
|
|
|
|
if TRACING_SUPPORT
|
|
|
|
|
|
2009-04-20 14:47:36 +00:00
|
|
|
menuconfig FTRACE
|
|
|
|
|
bool "Tracers"
|
2009-05-07 16:49:27 +00:00
|
|
|
default y if DEBUG_KERNEL
|
2009-04-20 14:47:36 +00:00
|
|
|
help
|
|
|
|
|
Enable the kernel tracing infrastructure.
|
|
|
|
|
|
|
|
|
|
if FTRACE
|
2008-10-21 14:31:18 +00:00
|
|
|
|
2008-10-06 23:06:12 +00:00
|
|
|
config FUNCTION_TRACER
|
ftrace: function tracer
This is a simple trace that uses the ftrace infrastructure. It is
designed to be fast and small, and easy to use. It is useful to
record things that happen over a very short period of time, and
not to analyze the system in general.
Updates:
available_tracers
"function" is added to this file.
current_tracer
To enable the function tracer:
echo function > /debugfs/tracing/current_tracer
To disable the tracer:
echo disable > /debugfs/tracing/current_tracer
The output of the function_trace file is as follows
"echo noverbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 0d.h. 1595128us+: set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper-0 0d.h. 1595131us+: _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
Or with verbose turned on:
"echo verbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
swapper 0 0 9 00000000 00000000 [f3675f41] 1595.128ms (+0.003ms): set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper 0 0 9 00000000 00000001 [f3675f45] 1595.131ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
swapper 0 0 9 00000000 00000002 [f3675f48] 1595.135ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
The "trace" file is not affected by the verbose mode, but is by the symonly.
echo "nosymonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479967] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <ffffffff80337a4d> <-- _spin_unlock_irqrestore+0xe/0x5a <ffffffff8048cc8f>
[ 81.479967] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <ffffffff8048ccbf> <-- sub_preempt_count+0xc/0x7a <ffffffff80233d7b>
[ 81.479968] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <ffffffff80233d9f> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
[ 81.479968] CPU 0: bash:3154 vfs_write+0x11d/0x155 <ffffffff8029a043> <-- dnotify_parent+0x12/0x78 <ffffffff802d54fb>
[ 81.479968] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <ffffffff802d5516> <-- _spin_lock+0xe/0x70 <ffffffff8048c910>
[ 81.479969] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <ffffffff8048c91d> <-- add_preempt_count+0xe/0x77 <ffffffff80233df7>
[ 81.479969] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <ffffffff80233e27> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
echo "symonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479913] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <-- _spin_unlock_irqrestore+0xe/0x5a
[ 81.479913] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <-- sub_preempt_count+0xc/0x7a
[ 81.479913] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <-- in_lock_functions+0x9/0x24
[ 81.479914] CPU 0: bash:3154 vfs_write+0x11d/0x155 <-- dnotify_parent+0x12/0x78
[ 81.479914] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <-- _spin_lock+0xe/0x70
[ 81.479914] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <-- add_preempt_count+0xe/0x77
[ 81.479914] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <-- in_lock_functions+0x9/0x24
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
bool "Kernel Function Tracer"
|
2008-10-06 23:06:12 +00:00
|
|
|
depends on HAVE_FUNCTION_TRACER
|
ftrace: function tracer
This is a simple trace that uses the ftrace infrastructure. It is
designed to be fast and small, and easy to use. It is useful to
record things that happen over a very short period of time, and
not to analyze the system in general.
Updates:
available_tracers
"function" is added to this file.
current_tracer
To enable the function tracer:
echo function > /debugfs/tracing/current_tracer
To disable the tracer:
echo disable > /debugfs/tracing/current_tracer
The output of the function_trace file is as follows
"echo noverbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 0d.h. 1595128us+: set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper-0 0d.h. 1595131us+: _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
Or with verbose turned on:
"echo verbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
swapper 0 0 9 00000000 00000000 [f3675f41] 1595.128ms (+0.003ms): set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper 0 0 9 00000000 00000001 [f3675f45] 1595.131ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
swapper 0 0 9 00000000 00000002 [f3675f48] 1595.135ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
The "trace" file is not affected by the verbose mode, but is by the symonly.
echo "nosymonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479967] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <ffffffff80337a4d> <-- _spin_unlock_irqrestore+0xe/0x5a <ffffffff8048cc8f>
[ 81.479967] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <ffffffff8048ccbf> <-- sub_preempt_count+0xc/0x7a <ffffffff80233d7b>
[ 81.479968] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <ffffffff80233d9f> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
[ 81.479968] CPU 0: bash:3154 vfs_write+0x11d/0x155 <ffffffff8029a043> <-- dnotify_parent+0x12/0x78 <ffffffff802d54fb>
[ 81.479968] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <ffffffff802d5516> <-- _spin_lock+0xe/0x70 <ffffffff8048c910>
[ 81.479969] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <ffffffff8048c91d> <-- add_preempt_count+0xe/0x77 <ffffffff80233df7>
[ 81.479969] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <ffffffff80233e27> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
echo "symonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479913] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <-- _spin_unlock_irqrestore+0xe/0x5a
[ 81.479913] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <-- sub_preempt_count+0xc/0x7a
[ 81.479913] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <-- in_lock_functions+0x9/0x24
[ 81.479914] CPU 0: bash:3154 vfs_write+0x11d/0x155 <-- dnotify_parent+0x12/0x78
[ 81.479914] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <-- _spin_lock+0xe/0x70
[ 81.479914] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <-- add_preempt_count+0xe/0x77
[ 81.479914] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <-- in_lock_functions+0x9/0x24
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
select FRAME_POINTER
|
2009-02-19 03:06:18 +00:00
|
|
|
select KALLSYMS
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-05-12 19:20:42 +00:00
|
|
|
select CONTEXT_SWITCH_TRACER
|
ftrace: function tracer
This is a simple trace that uses the ftrace infrastructure. It is
designed to be fast and small, and easy to use. It is useful to
record things that happen over a very short period of time, and
not to analyze the system in general.
Updates:
available_tracers
"function" is added to this file.
current_tracer
To enable the function tracer:
echo function > /debugfs/tracing/current_tracer
To disable the tracer:
echo disable > /debugfs/tracing/current_tracer
The output of the function_trace file is as follows
"echo noverbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 0d.h. 1595128us+: set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper-0 0d.h. 1595131us+: _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
Or with verbose turned on:
"echo verbose > /debugfs/tracing/iter_ctrl"
preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
swapper 0 0 9 00000000 00000000 [f3675f41] 1595.128ms (+0.003ms): set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper 0 0 9 00000000 00000001 [f3675f45] 1595.131ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
swapper 0 0 9 00000000 00000002 [f3675f48] 1595.135ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
The "trace" file is not affected by the verbose mode, but is by the symonly.
echo "nosymonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479967] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <ffffffff80337a4d> <-- _spin_unlock_irqrestore+0xe/0x5a <ffffffff8048cc8f>
[ 81.479967] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <ffffffff8048ccbf> <-- sub_preempt_count+0xc/0x7a <ffffffff80233d7b>
[ 81.479968] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <ffffffff80233d9f> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
[ 81.479968] CPU 0: bash:3154 vfs_write+0x11d/0x155 <ffffffff8029a043> <-- dnotify_parent+0x12/0x78 <ffffffff802d54fb>
[ 81.479968] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <ffffffff802d5516> <-- _spin_lock+0xe/0x70 <ffffffff8048c910>
[ 81.479969] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <ffffffff8048c91d> <-- add_preempt_count+0xe/0x77 <ffffffff80233df7>
[ 81.479969] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <ffffffff80233e27> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
echo "symonly" > /debugfs/tracing/iter_ctrl
tracer:
[ 81.479913] CPU 0: bash:3154 register_ftrace_function+0x5f/0x66 <-- _spin_unlock_irqrestore+0xe/0x5a
[ 81.479913] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <-- sub_preempt_count+0xc/0x7a
[ 81.479913] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <-- in_lock_functions+0x9/0x24
[ 81.479914] CPU 0: bash:3154 vfs_write+0x11d/0x155 <-- dnotify_parent+0x12/0x78
[ 81.479914] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <-- _spin_lock+0xe/0x70
[ 81.479914] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <-- add_preempt_count+0xe/0x77
[ 81.479914] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <-- in_lock_functions+0x9/0x24
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
help
|
|
|
|
|
Enable the kernel to trace every kernel function. This is done
|
|
|
|
|
by using a compiler feature to insert a small, 5-byte No-Operation
|
|
|
|
|
instruction to the beginning of every kernel function, which NOP
|
|
|
|
|
sequence is then dynamically patched into a tracer call when
|
|
|
|
|
tracing is enabled by the administrator. If it's runtime disabled
|
|
|
|
|
(the bootup default), then the overhead of the instructions is very
|
|
|
|
|
small and not measurable even in micro-benchmarks.
|
2008-05-12 19:20:42 +00:00
|
|
|
|
2008-11-25 20:07:04 +00:00
|
|
|
config FUNCTION_GRAPH_TRACER
|
|
|
|
|
bool "Kernel Function Graph Tracer"
|
|
|
|
|
depends on HAVE_FUNCTION_GRAPH_TRACER
|
2008-11-11 06:14:25 +00:00
|
|
|
depends on FUNCTION_TRACER
|
function-graph: disable when both x86_32 and optimize for size are configured
On x86_32, when optimize for size is set, gcc may align the frame pointer
and make a copy of the the return address inside the stack frame.
The return address that is located in the stack frame may not be
the one used to return to the calling function. This will break the
function graph tracer.
The function graph tracer replaces the return address with a jump to a hook
function that can trace the exit of the function. If it only replaces
a copy, then the hook will not be called when the function returns.
Worse yet, when the parent function returns, the function graph tracer
will return back to the location of the child function which will
easily crash the kernel with weird results.
To see the problem, when i386 is compiled with -Os we get:
c106be03: 57 push %edi
c106be04: 8d 7c 24 08 lea 0x8(%esp),%edi
c106be08: 83 e4 e0 and $0xffffffe0,%esp
c106be0b: ff 77 fc pushl 0xfffffffc(%edi)
c106be0e: 55 push %ebp
c106be0f: 89 e5 mov %esp,%ebp
c106be11: 57 push %edi
c106be12: 56 push %esi
c106be13: 53 push %ebx
c106be14: 81 ec 8c 00 00 00 sub $0x8c,%esp
c106be1a: e8 f5 57 fb ff call c1021614 <mcount>
When it is compiled with -O2 instead we get:
c10896f0: 55 push %ebp
c10896f1: 89 e5 mov %esp,%ebp
c10896f3: 83 ec 28 sub $0x28,%esp
c10896f6: 89 5d f4 mov %ebx,0xfffffff4(%ebp)
c10896f9: 89 75 f8 mov %esi,0xfffffff8(%ebp)
c10896fc: 89 7d fc mov %edi,0xfffffffc(%ebp)
c10896ff: e8 d0 08 fa ff call c1029fd4 <mcount>
The compile with -Os will align the stack pointer then set up the
frame pointer (%ebp), and it copies the return address back into
the stack frame. The change to the return address in mcount is done
to the copy and not the real place holder of the return address.
Then compile with -O2 sets up the frame pointer first, this makes
the change to the return address by mcount affect where the function
will jump on exit.
Reported-by: Jake Edge <jake@lwn.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-18 16:53:21 +00:00
|
|
|
depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
|
2008-12-03 09:33:58 +00:00
|
|
|
default y
|
2008-11-11 06:14:25 +00:00
|
|
|
help
|
2008-11-25 20:07:04 +00:00
|
|
|
Enable the kernel to trace a function at both its return
|
|
|
|
|
and its entry.
|
2009-01-26 10:12:25 +00:00
|
|
|
Its first purpose is to trace the duration of functions and
|
|
|
|
|
draw a call graph for each thread with some information like
|
|
|
|
|
the return value. This is done by setting the current return
|
|
|
|
|
address on the current task structure into a stack of calls.
|
2008-11-11 06:14:25 +00:00
|
|
|
|
2009-03-20 16:50:56 +00:00
|
|
|
|
2008-05-12 19:20:42 +00:00
|
|
|
config IRQSOFF_TRACER
|
|
|
|
|
bool "Interrupts-off Latency Tracer"
|
|
|
|
|
default n
|
|
|
|
|
depends on TRACE_IRQFLAGS_SUPPORT
|
|
|
|
|
depends on GENERIC_TIME
|
|
|
|
|
select TRACE_IRQFLAGS
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-05-12 19:20:42 +00:00
|
|
|
select TRACER_MAX_TRACE
|
2009-09-04 18:24:40 +00:00
|
|
|
select RING_BUFFER_ALLOW_SWAP
|
2008-05-12 19:20:42 +00:00
|
|
|
help
|
|
|
|
|
This option measures the time spent in irqs-off critical
|
|
|
|
|
sections, with microsecond accuracy.
|
|
|
|
|
|
|
|
|
|
The default measurement method is a maximum search, which is
|
|
|
|
|
disabled by default and can be runtime (re-)started
|
|
|
|
|
via:
|
|
|
|
|
|
2009-06-02 06:01:37 +00:00
|
|
|
echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
|
2008-05-12 19:20:42 +00:00
|
|
|
|
2008-05-12 19:20:42 +00:00
|
|
|
(Note that kernel size and overhead increases with this option
|
|
|
|
|
enabled. This option and the preempt-off timing option can be
|
|
|
|
|
used together or separately.)
|
|
|
|
|
|
|
|
|
|
config PREEMPT_TRACER
|
|
|
|
|
bool "Preemption-off Latency Tracer"
|
|
|
|
|
default n
|
|
|
|
|
depends on GENERIC_TIME
|
|
|
|
|
depends on PREEMPT
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-05-12 19:20:42 +00:00
|
|
|
select TRACER_MAX_TRACE
|
2009-09-04 18:24:40 +00:00
|
|
|
select RING_BUFFER_ALLOW_SWAP
|
2008-05-12 19:20:42 +00:00
|
|
|
help
|
|
|
|
|
This option measures the time spent in preemption off critical
|
|
|
|
|
sections, with microsecond accuracy.
|
|
|
|
|
|
|
|
|
|
The default measurement method is a maximum search, which is
|
|
|
|
|
disabled by default and can be runtime (re-)started
|
|
|
|
|
via:
|
|
|
|
|
|
2009-06-02 06:01:37 +00:00
|
|
|
echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
|
2008-05-12 19:20:42 +00:00
|
|
|
|
|
|
|
|
(Note that kernel size and overhead increases with this option
|
|
|
|
|
enabled. This option and the irqs-off timing option can be
|
|
|
|
|
used together or separately.)
|
|
|
|
|
|
2008-05-12 19:20:47 +00:00
|
|
|
config SYSPROF_TRACER
|
|
|
|
|
bool "Sysprof Tracer"
|
2008-05-24 13:00:46 +00:00
|
|
|
depends on X86
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-02-10 14:49:11 +00:00
|
|
|
select CONTEXT_SWITCH_TRACER
|
2008-05-12 19:20:47 +00:00
|
|
|
help
|
|
|
|
|
This tracer provides the trace needed by the 'Sysprof' userspace
|
|
|
|
|
tool.
|
|
|
|
|
|
2008-05-12 19:20:42 +00:00
|
|
|
config SCHED_TRACER
|
|
|
|
|
bool "Scheduling Latency Tracer"
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-05-12 19:20:42 +00:00
|
|
|
select CONTEXT_SWITCH_TRACER
|
|
|
|
|
select TRACER_MAX_TRACE
|
|
|
|
|
help
|
|
|
|
|
This tracer tracks the latency of the highest priority task
|
|
|
|
|
to be scheduled in, starting from the point it has woken up.
|
|
|
|
|
|
2009-05-28 20:31:21 +00:00
|
|
|
config ENABLE_DEFAULT_TRACERS
|
|
|
|
|
bool "Trace process context switches and events"
|
2009-05-28 19:50:13 +00:00
|
|
|
depends on !GENERIC_TRACER
|
2009-02-24 15:21:36 +00:00
|
|
|
select TRACING
|
|
|
|
|
help
|
|
|
|
|
This tracer hooks to various trace points in the kernel
|
|
|
|
|
allowing the user to pick and choose which trace point they
|
2009-05-28 20:31:21 +00:00
|
|
|
want to trace. It also includes the sched_switch tracer plugin.
|
2009-04-20 14:59:34 +00:00
|
|
|
|
2009-03-07 04:52:59 +00:00
|
|
|
config FTRACE_SYSCALLS
|
|
|
|
|
bool "Trace syscalls"
|
2009-08-24 21:43:11 +00:00
|
|
|
depends on HAVE_SYSCALL_TRACEPOINTS
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-03-15 21:10:38 +00:00
|
|
|
select KALLSYMS
|
2009-03-07 04:52:59 +00:00
|
|
|
help
|
|
|
|
|
Basic tracer to catch the syscall entry and exit events.
|
|
|
|
|
|
2008-09-23 10:36:20 +00:00
|
|
|
config BOOT_TRACER
|
|
|
|
|
bool "Trace boot initcalls"
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-10-22 17:26:23 +00:00
|
|
|
select CONTEXT_SWITCH_TRACER
|
2008-09-23 10:36:20 +00:00
|
|
|
help
|
|
|
|
|
This tracer helps developers to optimize boot times: it records
|
2008-10-14 12:27:20 +00:00
|
|
|
the timings of the initcalls and traces key events and the identity
|
|
|
|
|
of tasks that can cause boot delays, such as context-switches.
|
|
|
|
|
|
2009-06-29 07:55:10 +00:00
|
|
|
Its aim is to be parsed by the scripts/bootgraph.pl tool to
|
2008-10-14 12:27:20 +00:00
|
|
|
produce pretty graphics about boot inefficiencies, giving a visual
|
|
|
|
|
representation of the delays during initcalls - but the raw
|
|
|
|
|
/debug/tracing/trace text output is readable too.
|
|
|
|
|
|
2009-06-29 07:55:10 +00:00
|
|
|
You must pass in initcall_debug and ftrace=initcall to the kernel
|
|
|
|
|
command line to enable this on bootup.
|
2008-09-23 10:36:20 +00:00
|
|
|
|
2008-11-12 20:24:24 +00:00
|
|
|
config TRACE_BRANCH_PROFILING
|
2009-04-20 14:27:58 +00:00
|
|
|
bool
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-04-20 14:27:58 +00:00
|
|
|
|
|
|
|
|
choice
|
|
|
|
|
prompt "Branch Profiling"
|
|
|
|
|
default BRANCH_PROFILE_NONE
|
|
|
|
|
help
|
|
|
|
|
The branch profiling is a software profiler. It will add hooks
|
|
|
|
|
into the C conditionals to test which path a branch takes.
|
|
|
|
|
|
|
|
|
|
The likely/unlikely profiler only looks at the conditions that
|
|
|
|
|
are annotated with a likely or unlikely macro.
|
|
|
|
|
|
|
|
|
|
The "all branch" profiler will profile every if statement in the
|
|
|
|
|
kernel. This profiler will also enable the likely/unlikely
|
|
|
|
|
profiler as well.
|
|
|
|
|
|
|
|
|
|
Either of the above profilers add a bit of overhead to the system.
|
|
|
|
|
If unsure choose "No branch profiling".
|
|
|
|
|
|
|
|
|
|
config BRANCH_PROFILE_NONE
|
|
|
|
|
bool "No branch profiling"
|
|
|
|
|
help
|
|
|
|
|
No branch profiling. Branch profiling adds a bit of overhead.
|
|
|
|
|
Only enable it if you want to analyse the branching behavior.
|
|
|
|
|
Otherwise keep it disabled.
|
|
|
|
|
|
|
|
|
|
config PROFILE_ANNOTATED_BRANCHES
|
|
|
|
|
bool "Trace likely/unlikely profiler"
|
|
|
|
|
select TRACE_BRANCH_PROFILING
|
2008-11-12 05:14:39 +00:00
|
|
|
help
|
|
|
|
|
This tracer profiles all the the likely and unlikely macros
|
|
|
|
|
in the kernel. It will display the results in:
|
|
|
|
|
|
2009-06-02 06:01:37 +00:00
|
|
|
/sys/kernel/debug/tracing/profile_annotated_branch
|
2008-11-12 05:14:39 +00:00
|
|
|
|
|
|
|
|
Note: this will add a significant overhead, only turn this
|
|
|
|
|
on if you need to profile the system's use of these macros.
|
|
|
|
|
|
2008-11-21 06:30:54 +00:00
|
|
|
config PROFILE_ALL_BRANCHES
|
|
|
|
|
bool "Profile all if conditionals"
|
2009-04-20 14:27:58 +00:00
|
|
|
select TRACE_BRANCH_PROFILING
|
2008-11-21 06:30:54 +00:00
|
|
|
help
|
|
|
|
|
This tracer profiles all branch conditions. Every if ()
|
|
|
|
|
taken in the kernel is recorded whether it hit or miss.
|
|
|
|
|
The results will be displayed in:
|
|
|
|
|
|
2009-06-02 06:01:37 +00:00
|
|
|
/sys/kernel/debug/tracing/profile_branch
|
2008-11-21 06:30:54 +00:00
|
|
|
|
2009-04-20 14:27:58 +00:00
|
|
|
This option also enables the likely/unlikely profiler.
|
|
|
|
|
|
2008-11-21 06:30:54 +00:00
|
|
|
This configuration, when enabled, will impose a great overhead
|
|
|
|
|
on the system. This should only be enabled when the system
|
|
|
|
|
is to be analyzed
|
2009-04-20 14:27:58 +00:00
|
|
|
endchoice
|
2008-11-21 06:30:54 +00:00
|
|
|
|
2008-11-12 20:24:24 +00:00
|
|
|
config TRACING_BRANCHES
|
2008-11-12 05:14:40 +00:00
|
|
|
bool
|
|
|
|
|
help
|
|
|
|
|
Selected by tracers that will trace the likely and unlikely
|
|
|
|
|
conditions. This prevents the tracers themselves from being
|
|
|
|
|
profiled. Profiling the tracing infrastructure can only happen
|
|
|
|
|
when the likelys and unlikelys are not being traced.
|
|
|
|
|
|
2008-11-12 20:24:24 +00:00
|
|
|
config BRANCH_TRACER
|
2008-11-12 05:14:40 +00:00
|
|
|
bool "Trace likely/unlikely instances"
|
2008-11-12 20:24:24 +00:00
|
|
|
depends on TRACE_BRANCH_PROFILING
|
|
|
|
|
select TRACING_BRANCHES
|
2008-11-12 05:14:40 +00:00
|
|
|
help
|
|
|
|
|
This traces the events of likely and unlikely condition
|
|
|
|
|
calls in the kernel. The difference between this and the
|
|
|
|
|
"Trace likely/unlikely profiler" is that this is not a
|
|
|
|
|
histogram of the callers, but actually places the calling
|
|
|
|
|
events into a running trace buffer to see when and where the
|
|
|
|
|
events happened, as well as their results.
|
|
|
|
|
|
|
|
|
|
Say N if unsure.
|
|
|
|
|
|
2008-11-24 00:49:58 +00:00
|
|
|
config POWER_TRACER
|
|
|
|
|
bool "Trace power consumption behavior"
|
|
|
|
|
depends on X86
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-11-24 00:49:58 +00:00
|
|
|
help
|
|
|
|
|
This tracer helps developers to analyze and optimize the kernels
|
|
|
|
|
power management decisions, specifically the C-state and P-state
|
|
|
|
|
behavior.
|
|
|
|
|
|
|
|
|
|
|
2008-08-28 03:31:01 +00:00
|
|
|
config STACK_TRACER
|
|
|
|
|
bool "Trace max stack"
|
2008-10-06 23:06:12 +00:00
|
|
|
depends on HAVE_FUNCTION_TRACER
|
|
|
|
|
select FUNCTION_TRACER
|
2008-08-28 03:31:01 +00:00
|
|
|
select STACKTRACE
|
2009-02-19 03:06:18 +00:00
|
|
|
select KALLSYMS
|
2008-08-28 03:31:01 +00:00
|
|
|
help
|
2008-10-14 12:15:43 +00:00
|
|
|
This special tracer records the maximum stack footprint of the
|
2009-06-02 06:01:37 +00:00
|
|
|
kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
|
2008-10-14 12:15:43 +00:00
|
|
|
|
|
|
|
|
This tracer works by hooking into every function call that the
|
|
|
|
|
kernel executes, and keeping a maximum stack depth value and
|
2008-12-17 04:06:40 +00:00
|
|
|
stack-trace saved. If this is configured with DYNAMIC_FTRACE
|
|
|
|
|
then it will not have any overhead while the stack tracer
|
|
|
|
|
is disabled.
|
|
|
|
|
|
|
|
|
|
To enable the stack tracer on bootup, pass in 'stacktrace'
|
|
|
|
|
on the kernel command line.
|
|
|
|
|
|
|
|
|
|
The stack tracer can also be enabled or disabled via the
|
|
|
|
|
sysctl kernel.stack_tracer_enabled
|
2008-10-14 12:15:43 +00:00
|
|
|
|
|
|
|
|
Say N if unsure.
|
2008-08-28 03:31:01 +00:00
|
|
|
|
2008-12-11 12:53:26 +00:00
|
|
|
config HW_BRANCH_TRACER
|
2008-11-25 08:24:15 +00:00
|
|
|
depends on HAVE_HW_BRANCH_TRACER
|
2008-12-11 12:53:26 +00:00
|
|
|
bool "Trace hw branches"
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-11-25 08:24:15 +00:00
|
|
|
help
|
|
|
|
|
This tracer records all branches on the system in a circular
|
|
|
|
|
buffer giving access to the last N branches for each cpu.
|
|
|
|
|
|
2008-12-29 21:42:23 +00:00
|
|
|
config KMEMTRACE
|
|
|
|
|
bool "Trace SLAB allocations"
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2008-12-29 21:42:23 +00:00
|
|
|
help
|
|
|
|
|
kmemtrace provides tracing for slab allocator functions, such as
|
|
|
|
|
kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
|
|
|
|
|
data is then fed to the userspace application in order to analyse
|
|
|
|
|
allocation hotspots, internal fragmentation and so on, making it
|
|
|
|
|
possible to see how well an allocator performs, as well as debug
|
|
|
|
|
and profile kernel code.
|
|
|
|
|
|
|
|
|
|
This requires an userspace application to use. See
|
2009-04-10 00:48:36 +00:00
|
|
|
Documentation/trace/kmemtrace.txt for more information.
|
2008-12-29 21:42:23 +00:00
|
|
|
|
|
|
|
|
Saying Y will make the kernel somewhat larger and slower. However,
|
|
|
|
|
if you disable kmemtrace at run-time or boot-time, the performance
|
|
|
|
|
impact is minimal (depending on the arch the kernel is built for).
|
|
|
|
|
|
|
|
|
|
If unsure, say N.
|
|
|
|
|
|
2009-01-12 22:15:46 +00:00
|
|
|
config WORKQUEUE_TRACER
|
|
|
|
|
bool "Trace workqueues"
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-01-12 22:15:46 +00:00
|
|
|
help
|
|
|
|
|
The workqueue tracer provides some statistical informations
|
|
|
|
|
about each cpu workqueue thread such as the number of the
|
|
|
|
|
works inserted and executed since their creation. It can help
|
|
|
|
|
to evaluate the amount of work each of them have to perform.
|
|
|
|
|
For example it can help a developer to decide whether he should
|
|
|
|
|
choose a per cpu workqueue instead of a singlethreaded one.
|
|
|
|
|
|
2009-02-07 19:46:45 +00:00
|
|
|
config BLK_DEV_IO_TRACE
|
|
|
|
|
bool "Support for tracing block io actions"
|
|
|
|
|
depends on SYSFS
|
2009-02-09 11:06:54 +00:00
|
|
|
depends on BLOCK
|
2009-02-07 19:46:45 +00:00
|
|
|
select RELAY
|
|
|
|
|
select DEBUG_FS
|
|
|
|
|
select TRACEPOINTS
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-02-07 19:46:45 +00:00
|
|
|
select STACKTRACE
|
|
|
|
|
help
|
|
|
|
|
Say Y here if you want to be able to trace the block layer actions
|
|
|
|
|
on a given queue. Tracing allows you to see any traffic happening
|
|
|
|
|
on a block device queue. For more information (and the userspace
|
|
|
|
|
support tools needed), fetch the blktrace tools from:
|
|
|
|
|
|
|
|
|
|
git://git.kernel.dk/blktrace.git
|
|
|
|
|
|
|
|
|
|
Tracing also is possible using the ftrace interface, e.g.:
|
|
|
|
|
|
|
|
|
|
echo 1 > /sys/block/sda/sda1/trace/enable
|
|
|
|
|
echo blk > /sys/kernel/debug/tracing/current_tracer
|
|
|
|
|
cat /sys/kernel/debug/tracing/trace_pipe
|
|
|
|
|
|
|
|
|
|
If unsure, say N.
|
2008-12-29 21:42:23 +00:00
|
|
|
|
ftrace: dynamic enabling/disabling of function calls
This patch adds a feature to dynamically replace the ftrace code
with the jmps to allow a kernel with ftrace configured to run
as fast as it can without it configured.
The way this works, is on bootup (if ftrace is enabled), a ftrace
function is registered to record the instruction pointer of all
places that call the function.
Later, if there's still any code to patch, a kthread is awoken
(rate limited to at most once a second) that performs a stop_machine,
and replaces all the code that was called with a jmp over the call
to ftrace. It only replaces what was found the previous time. Typically
the system reaches equilibrium quickly after bootup and there's no code
patching needed at all.
e.g.
call ftrace /* 5 bytes */
is replaced with
jmp 3f /* jmp is 2 bytes and we jump 3 forward */
3:
When we want to enable ftrace for function tracing, the IP recording
is removed, and stop_machine is called again to replace all the locations
of that were recorded back to the call of ftrace. When it is disabled,
we replace the code back to the jmp.
Allocation is done by the kthread. If the ftrace recording function is
called, and we don't have any record slots available, then we simply
skip that call. Once a second a new page (if needed) is allocated for
recording new ftrace function calls. A large batch is allocated at
boot up to get most of the calls there.
Because we do this via stop_machine, we don't have to worry about another
CPU executing a ftrace call as we modify it. But we do need to worry
about NMI's so all functions that might be called via nmi must be
annotated with notrace_nmi. When this code is configured in, the NMI code
will not call notrace.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
config DYNAMIC_FTRACE
|
|
|
|
|
bool "enable/disable ftrace tracepoints dynamically"
|
2008-10-06 23:06:12 +00:00
|
|
|
depends on FUNCTION_TRACER
|
2008-05-17 04:01:36 +00:00
|
|
|
depends on HAVE_DYNAMIC_FTRACE
|
ftrace: dynamic enabling/disabling of function calls
This patch adds a feature to dynamically replace the ftrace code
with the jmps to allow a kernel with ftrace configured to run
as fast as it can without it configured.
The way this works, is on bootup (if ftrace is enabled), a ftrace
function is registered to record the instruction pointer of all
places that call the function.
Later, if there's still any code to patch, a kthread is awoken
(rate limited to at most once a second) that performs a stop_machine,
and replaces all the code that was called with a jmp over the call
to ftrace. It only replaces what was found the previous time. Typically
the system reaches equilibrium quickly after bootup and there's no code
patching needed at all.
e.g.
call ftrace /* 5 bytes */
is replaced with
jmp 3f /* jmp is 2 bytes and we jump 3 forward */
3:
When we want to enable ftrace for function tracing, the IP recording
is removed, and stop_machine is called again to replace all the locations
of that were recorded back to the call of ftrace. When it is disabled,
we replace the code back to the jmp.
Allocation is done by the kthread. If the ftrace recording function is
called, and we don't have any record slots available, then we simply
skip that call. Once a second a new page (if needed) is allocated for
recording new ftrace function calls. A large batch is allocated at
boot up to get most of the calls there.
Because we do this via stop_machine, we don't have to worry about another
CPU executing a ftrace call as we modify it. But we do need to worry
about NMI's so all functions that might be called via nmi must be
annotated with notrace_nmi. When this code is configured in, the NMI code
will not call notrace.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
default y
|
|
|
|
|
help
|
|
|
|
|
This option will modify all the calls to ftrace dynamically
|
|
|
|
|
(will patch them out of the binary image and replaces them
|
|
|
|
|
with a No-Op instruction) as they are called. A table is
|
|
|
|
|
created to dynamically enable them again.
|
|
|
|
|
|
2008-10-06 23:06:12 +00:00
|
|
|
This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
|
ftrace: dynamic enabling/disabling of function calls
This patch adds a feature to dynamically replace the ftrace code
with the jmps to allow a kernel with ftrace configured to run
as fast as it can without it configured.
The way this works, is on bootup (if ftrace is enabled), a ftrace
function is registered to record the instruction pointer of all
places that call the function.
Later, if there's still any code to patch, a kthread is awoken
(rate limited to at most once a second) that performs a stop_machine,
and replaces all the code that was called with a jmp over the call
to ftrace. It only replaces what was found the previous time. Typically
the system reaches equilibrium quickly after bootup and there's no code
patching needed at all.
e.g.
call ftrace /* 5 bytes */
is replaced with
jmp 3f /* jmp is 2 bytes and we jump 3 forward */
3:
When we want to enable ftrace for function tracing, the IP recording
is removed, and stop_machine is called again to replace all the locations
of that were recorded back to the call of ftrace. When it is disabled,
we replace the code back to the jmp.
Allocation is done by the kthread. If the ftrace recording function is
called, and we don't have any record slots available, then we simply
skip that call. Once a second a new page (if needed) is allocated for
recording new ftrace function calls. A large batch is allocated at
boot up to get most of the calls there.
Because we do this via stop_machine, we don't have to worry about another
CPU executing a ftrace call as we modify it. But we do need to worry
about NMI's so all functions that might be called via nmi must be
annotated with notrace_nmi. When this code is configured in, the NMI code
will not call notrace.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-12 19:20:42 +00:00
|
|
|
has native performance as long as no tracing is active.
|
|
|
|
|
|
|
|
|
|
The changes to the code are done by a kernel thread that
|
|
|
|
|
wakes up once a second and checks to see if any ftrace calls
|
|
|
|
|
were made. If so, it runs stop_machine (stops all CPUS)
|
|
|
|
|
and modifies the code to jump over the call to ftrace.
|
2008-05-12 19:20:44 +00:00
|
|
|
|
2009-03-20 16:50:56 +00:00
|
|
|
config FUNCTION_PROFILER
|
|
|
|
|
bool "Kernel function profiler"
|
2009-03-23 21:12:36 +00:00
|
|
|
depends on FUNCTION_TRACER
|
2009-03-20 16:50:56 +00:00
|
|
|
default n
|
|
|
|
|
help
|
2009-03-23 21:12:36 +00:00
|
|
|
This option enables the kernel function profiler. A file is created
|
|
|
|
|
in debugfs called function_profile_enabled which defaults to zero.
|
2009-03-20 16:50:56 +00:00
|
|
|
When a 1 is echoed into this file profiling begins, and when a
|
|
|
|
|
zero is entered, profiling stops. A file in the trace_stats
|
|
|
|
|
directory called functions, that show the list of functions that
|
|
|
|
|
have been hit and their counters.
|
|
|
|
|
|
|
|
|
|
If in doubt, say N
|
|
|
|
|
|
ftrace: create __mcount_loc section
This patch creates a section in the kernel called "__mcount_loc".
This will hold a list of pointers to the mcount relocation for
each call site of mcount.
For example:
objdump -dr init/main.o
[...]
Disassembly of section .text:
0000000000000000 <do_one_initcall>:
0: 55 push %rbp
[...]
000000000000017b <init_post>:
17b: 55 push %rbp
17c: 48 89 e5 mov %rsp,%rbp
17f: 53 push %rbx
180: 48 83 ec 08 sub $0x8,%rsp
184: e8 00 00 00 00 callq 189 <init_post+0xe>
185: R_X86_64_PC32 mcount+0xfffffffffffffffc
[...]
We will add a section to point to each function call.
.section __mcount_loc,"a",@progbits
[...]
.quad .text + 0x185
[...]
The offset to of the mcount call site in init_post is an offset from
the start of the section, and not the start of the function init_post.
The mcount relocation is at the call site 0x185 from the start of the
.text section.
.text + 0x185 == init_post + 0xa
We need a way to add this __mcount_loc section in a way that we do not
lose the relocations after final link. The .text section here will
be attached to all other .text sections after final link and the
offsets will be meaningless. We need to keep track of where these
.text sections are.
To do this, we use the start of the first function in the section.
do_one_initcall. We can make a tmp.s file with this function as a reference
to the start of the .text section.
.section __mcount_loc,"a",@progbits
[...]
.quad do_one_initcall + 0x185
[...]
Then we can compile the tmp.s into a tmp.o
gcc -c tmp.s -o tmp.o
And link it into back into main.o.
ld -r main.o tmp.o -o tmp_main.o
mv tmp_main.o main.o
But we have a problem. What happens if the first function in a section
is not exported, and is a static function. The linker will not let
the tmp.o use it. This case exists in main.o as well.
Disassembly of section .init.text:
0000000000000000 <set_reset_devices>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: e8 00 00 00 00 callq 9 <set_reset_devices+0x9>
5: R_X86_64_PC32 mcount+0xfffffffffffffffc
The first function in .init.text is a static function.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
The lowercase 't' means that set_reset_devices is local and is not exported.
If we simply try to link the tmp.o with the set_reset_devices we end
up with two symbols: one local and one global.
.section __mcount_loc,"a",@progbits
.quad set_reset_devices + 0x10
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
U set_reset_devices
We still have an undefined reference to set_reset_devices, and if we try
to compile the kernel, we will end up with an undefined reference to
set_reset_devices, or even worst, it could be exported someplace else,
and then we will have a reference to the wrong location.
To handle this case, we make an intermediate step using objcopy.
We convert set_reset_devices into a global exported symbol before linking
it with tmp.o and set it back afterwards.
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 T set_reset_devices
00000000000000a8 t __setup_set_reset_devices
000000000000105f t __setup_str_set_reset_devices
0000000000000000 t set_reset_devices
Now we have a section in main.o called __mcount_loc that we can place
somewhere in the kernel using vmlinux.ld.S and access it to convert
all these locations that call mcount into nops before starting SMP
and thus, eliminating the need to do this with kstop_machine.
Note, A well documented perl script (scripts/recordmcount.pl) is used
to do all this in one location.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-14 19:45:07 +00:00
|
|
|
config FTRACE_MCOUNT_RECORD
|
|
|
|
|
def_bool y
|
|
|
|
|
depends on DYNAMIC_FTRACE
|
|
|
|
|
depends on HAVE_FTRACE_MCOUNT_RECORD
|
|
|
|
|
|
2008-05-12 19:20:44 +00:00
|
|
|
config FTRACE_SELFTEST
|
|
|
|
|
bool
|
|
|
|
|
|
|
|
|
|
config FTRACE_STARTUP_TEST
|
|
|
|
|
bool "Perform a startup test on ftrace"
|
2009-05-28 19:50:13 +00:00
|
|
|
depends on GENERIC_TRACER
|
2008-05-12 19:20:44 +00:00
|
|
|
select FTRACE_SELFTEST
|
|
|
|
|
help
|
|
|
|
|
This option performs a series of startup tests on ftrace. On bootup
|
|
|
|
|
a series of tests are made to verify that the tracer is
|
|
|
|
|
functioning properly. It will do tests on all the configured
|
|
|
|
|
tracers of ftrace.
|
2008-10-21 14:31:18 +00:00
|
|
|
|
2009-09-14 15:58:24 +00:00
|
|
|
config EVENT_TRACE_TEST_SYSCALLS
|
|
|
|
|
bool "Run selftest on syscall events"
|
|
|
|
|
depends on FTRACE_STARTUP_TEST
|
|
|
|
|
help
|
|
|
|
|
This option will also enable testing every syscall event.
|
|
|
|
|
It only enables the event and disables it and runs various loads
|
|
|
|
|
with the event enabled. This adds a bit more time for kernel boot
|
|
|
|
|
up since it runs this on every system call defined.
|
|
|
|
|
|
|
|
|
|
TBD - enable a way to actually call the syscalls as we test their
|
|
|
|
|
events
|
|
|
|
|
|
2009-01-03 19:23:51 +00:00
|
|
|
config MMIOTRACE
|
|
|
|
|
bool "Memory mapped IO tracing"
|
2009-03-05 20:19:55 +00:00
|
|
|
depends on HAVE_MMIOTRACE_SUPPORT && PCI
|
2009-05-28 19:50:13 +00:00
|
|
|
select GENERIC_TRACER
|
2009-01-03 19:23:51 +00:00
|
|
|
help
|
|
|
|
|
Mmiotrace traces Memory Mapped I/O access and is meant for
|
|
|
|
|
debugging and reverse engineering. It is called from the ioremap
|
|
|
|
|
implementation and works via page faults. Tracing is disabled by
|
|
|
|
|
default and can be enabled at run-time.
|
|
|
|
|
|
2009-04-10 00:48:36 +00:00
|
|
|
See Documentation/trace/mmiotrace.txt.
|
2009-01-03 19:23:51 +00:00
|
|
|
If you are not helping to develop drivers, say N.
|
|
|
|
|
|
|
|
|
|
config MMIOTRACE_TEST
|
|
|
|
|
tristate "Test module for mmiotrace"
|
|
|
|
|
depends on MMIOTRACE && m
|
|
|
|
|
help
|
|
|
|
|
This is a dumb module for testing mmiotrace. It is very dangerous
|
|
|
|
|
as it will write garbage to IO memory starting at a given address.
|
|
|
|
|
However, it should be safe to use on e.g. unused portion of VRAM.
|
|
|
|
|
|
|
|
|
|
Say N, unless you absolutely know what you are doing.
|
|
|
|
|
|
2009-05-06 02:47:18 +00:00
|
|
|
config RING_BUFFER_BENCHMARK
|
|
|
|
|
tristate "Ring buffer benchmark stress tester"
|
|
|
|
|
depends on RING_BUFFER
|
|
|
|
|
help
|
|
|
|
|
This option creates a test to stress the ring buffer and bench mark it.
|
|
|
|
|
It creates its own ring buffer such that it will not interfer with
|
|
|
|
|
any other users of the ring buffer (such as ftrace). It then creates
|
|
|
|
|
a producer and consumer that will run for 10 seconds and sleep for
|
|
|
|
|
10 seconds. Each interval it will print out the number of events
|
|
|
|
|
it recorded and give a rough estimate of how long each iteration took.
|
|
|
|
|
|
|
|
|
|
It does not disable interrupts or raise its priority, so it may be
|
|
|
|
|
affected by processes that are running.
|
|
|
|
|
|
|
|
|
|
If unsure, say N
|
|
|
|
|
|
2009-04-20 14:47:36 +00:00
|
|
|
endif # FTRACE
|
2009-03-05 20:19:55 +00:00
|
|
|
|
|
|
|
|
endif # TRACING_SUPPORT
|
|
|
|
|
|
