forked from Minki/linux
acac03fa15
Sometimes there is a need to use perf in "live-log" mode. The problem
is, for seldom events, actual info output is largely delayed because
perf-record reads sample data in whole pages.
So for such scenarious, add flag for perf-record to go in "nodelay"
mode. To track e.g. what's going on in icmp_rcv while ping is running
Use it with something like this:
(1) $ perf probe -L icmp_rcv | grep -U8 '^ *43\>'
goto error;
}
38 if (!pskb_pull(skb, sizeof(*icmph)))
goto error;
icmph = icmp_hdr(skb);
43 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
/*
* 18 is the highest 'known' ICMP type. Anything else is a mystery
*
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
* discarded.
*/
50 if (icmph->type > NR_ICMP_TYPES)
goto error;
$ perf probe icmp_rcv:43 'type=icmph->type'
(2) $ cat trace-icmp.py
[...]
def trace_begin():
print "in trace_begin"
def trace_end():
print "in trace_end"
def probe__icmp_rcv(event_name, context, common_cpu,
common_secs, common_nsecs, common_pid, common_comm,
__probe_ip, type):
print_header(event_name, common_cpu, common_secs, common_nsecs,
common_pid, common_comm)
print "__probe_ip=%u, type=%u\n" % \
(__probe_ip, type),
[...]
(3) $ perf record -a -D -e probe:icmp_rcv -o - | \
perf script -i - -s trace-icmp.py
Thanks to Peter Zijlstra for pointing how to do it.
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20110112140613.GA11698@tugrik.mns.mnsspb.ru>
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
143 lines
3.0 KiB
Plaintext
143 lines
3.0 KiB
Plaintext
perf-record(1)
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==============
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NAME
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----
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perf-record - Run a command and record its profile into perf.data
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SYNOPSIS
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--------
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[verse]
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'perf record' [-e <EVENT> | --event=EVENT] [-l] [-a] <command>
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'perf record' [-e <EVENT> | --event=EVENT] [-l] [-a] -- <command> [<options>]
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DESCRIPTION
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-----------
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This command runs a command and gathers a performance counter profile
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from it, into perf.data - without displaying anything.
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This file can then be inspected later on, using 'perf report'.
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OPTIONS
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-------
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<command>...::
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Any command you can specify in a shell.
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-e::
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--event=::
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Select the PMU event. Selection can be:
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- a symbolic event name (use 'perf list' to list all events)
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- a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a
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hexadecimal event descriptor.
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- a hardware breakpoint event in the form of '\mem:addr[:access]'
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where addr is the address in memory you want to break in.
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Access is the memory access type (read, write, execute) it can
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be passed as follows: '\mem:addr[:[r][w][x]]'.
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If you want to profile read-write accesses in 0x1000, just set
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'mem:0x1000:rw'.
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--filter=<filter>::
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Event filter.
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-a::
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--all-cpus::
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System-wide collection from all CPUs.
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-l::
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Scale counter values.
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-p::
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--pid=::
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Record events on existing process ID.
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-t::
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--tid=::
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Record events on existing thread ID.
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-r::
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--realtime=::
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Collect data with this RT SCHED_FIFO priority.
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-D::
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--no-delay::
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Collect data without buffering.
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-A::
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--append::
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Append to the output file to do incremental profiling.
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-f::
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--force::
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Overwrite existing data file. (deprecated)
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-c::
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--count=::
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Event period to sample.
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-o::
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--output=::
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Output file name.
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-i::
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--no-inherit::
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Child tasks do not inherit counters.
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-F::
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--freq=::
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Profile at this frequency.
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-m::
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--mmap-pages=::
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Number of mmap data pages.
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-g::
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--call-graph::
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Do call-graph (stack chain/backtrace) recording.
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-q::
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--quiet::
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Don't print any message, useful for scripting.
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-v::
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--verbose::
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Be more verbose (show counter open errors, etc).
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-s::
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--stat::
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Per thread counts.
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-d::
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--data::
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Sample addresses.
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-T::
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--timestamp::
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Sample timestamps. Use it with 'perf report -D' to see the timestamps,
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for instance.
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-n::
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--no-samples::
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Don't sample.
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-R::
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--raw-samples::
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Collect raw sample records from all opened counters (default for tracepoint counters).
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-C::
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--cpu::
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Collect samples only on the list of CPUs provided. Multiple CPUs can be provided as a
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comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
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In per-thread mode with inheritance mode on (default), samples are captured only when
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the thread executes on the designated CPUs. Default is to monitor all CPUs.
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-N::
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--no-buildid-cache::
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Do not update the builid cache. This saves some overhead in situations
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where the information in the perf.data file (which includes buildids)
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is sufficient.
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SEE ALSO
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--------
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linkperf:perf-stat[1], linkperf:perf-list[1]
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