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ftrace: Access ret_stack->subtime only in the function profiler

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The subtime is used only for function profiler with function graph
tracer enabled.  Move the definition of subtime under
CONFIG_FUNCTION_PROFILER to reduce the memory usage.  Also move the
initialization of subtime into the graph entry callback.

Link: http://lkml.kernel.org/r/20160831025529.24018-1-namhyung@kernel.org

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Namhyung Kim 2016-08-31 11:55:29 +09:00 committed by Steven Rostedt
parent 613dccdf68
commit 8861dd303c
4 changed files with 13 additions and 6 deletions
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10
Documentation/trace/ftrace.txt
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@ -858,11 +858,11 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
When enabled, it will account time the task has been
scheduled out as part of the function call.
graph-time - When running function graph tracer, to include the
time to call nested functions. When this is not set,
the time reported for the function will only include
the time the function itself executed for, not the time
for functions that it called.
graph-time - When running function profiler with function graph tracer,
to include the time to call nested functions. When this is
not set, the time reported for the function will only
include the time the function itself executed for, not the
time for functions that it called.
record-cmd - When any event or tracer is enabled, a hook is enabled
in the sched_switch trace point to fill comm cache

2
include/linux/ftrace.h
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@ -794,7 +794,9 @@ struct ftrace_ret_stack {
unsigned long ret;
unsigned long func;
unsigned long long calltime;
#ifdef CONFIG_FUNCTION_PROFILER
unsigned long long subtime;
#endif
unsigned long fp;
};

6
kernel/trace/ftrace.c
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@ -872,7 +872,13 @@ function_profile_call(unsigned long ip, unsigned long parent_ip,
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int profile_graph_entry(struct ftrace_graph_ent *trace)
{
int index = trace->depth;
function_profile_call(trace->func, 0, NULL, NULL);
if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
current->ret_stack[index].subtime = 0;
return 1;
}

1
kernel/trace/trace_functions_graph.c
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@ -170,7 +170,6 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
current->ret_stack[index].ret = ret;
current->ret_stack[index].func = func;
current->ret_stack[index].calltime = calltime;
current->ret_stack[index].subtime = 0;
current->ret_stack[index].fp = frame_pointer;
*depth = current->curr_ret_stack;