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Commit 4ba1faa1 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
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perf record: Allow filtering perf's pid via --exclude-perf 



This patch allows 'perf record' to exclude events issued by perf itself
by '--exclude-perf' option.

Before this patch, when doing something like:

 # perf record -a -e syscalls:sys_enter_write <cmd>

One could easily get result like this:

 # /tmp/perf report --stdio
 ...
  # Overhead  Command  Shared Object       Symbol
  # ........  .......  ..................  ....................
  #
      99.99%  perf     libpthread-2.18.so  [.] __write_nocancel
      0.01%   ls       libc-2.18.so        [.] write
      0.01%   sshd     libc-2.18.so        [.] write
 ...

Where most events are generated by perf itself.

A shell trick can be done to filter perf itself out:

 # cat << EOF > ./tmp
 > #!/bin/sh
 > exec perf record -e ... --filter="common_pid != \$\$" -a sleep 10
 > EOF
 # chmod a+x ./tmp
 # ./tmp

However, doing so is user unfriendly.

This patch extracts evsel iteration framework introduced by patch 'perf
record: Apply filter to all events in a glob matching' into
foreach_evsel_in_last_glob(), and makes exclude_perf() function append
new filter expression to each evsel selected by a '-e' selector.

To avoid losing filters if user pass '--filter' after '--exclude-perf',
this patch uses perf_evsel__append_filter() in both case, instead of
perf_evsel__set_filter() which removes old filter. As a side effect, now
it is possible to use multiple '--filter' option for one selector. They
are combinded with '&&'.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1436513770-8896-2-git-send-email-wangnan0@huawei.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 15bfd2cc

tools/perf/Documentation/perf-record.txt

+10 −1
Original line number Diff line number Diff line
@@ -69,7 +69,16 @@ OPTIONS 
	  "perf report" to view group events together.



--filter=<filter>::

        Event filter.

        Event filter. This option should follow a event selector (-e) which

	selects tracepoint event(s). Multiple '--filter' options are combined

	using '&&'.



--exclude-perf::

	Don't record events issued by perf itself. This option should follow

	a event selector (-e) which selects tracepoint event(s). It adds a

	filter expression 'common_pid != $PERFPID' to filters. If other

	'--filter' exists, the new filter expression will be combined with

	them by '&&'.



-a::

--all-cpus::

tools/perf/builtin-record.c

+3 −0
Original line number Diff line number Diff line
@@ -992,6 +992,9 @@ struct option __record_options[] = { 
		     parse_events_option),

	OPT_CALLBACK(0, "filter", &record.evlist, "filter",

		     "event filter", parse_filter),

	OPT_CALLBACK_NOOPT(0, "exclude-perf", &record.evlist,

			   NULL, "don't record events from perf itself",

			   exclude_perf),

	OPT_STRING('p', "pid", &record.opts.target.pid, "pid",

		    "record events on existing process id"),

	OPT_STRING('t', "tid", &record.opts.target.tid, "tid",

tools/perf/util/parse-events.c

+70 −13
Original line number Diff line number Diff line
@@ -1167,36 +1167,93 @@ int parse_events_option(const struct option *opt, const char *str, 
	return ret;

}



int parse_filter(const struct option *opt, const char *str,

		 int unset __maybe_unused)

static int

foreach_evsel_in_last_glob(struct perf_evlist *evlist,

			   int (*func)(struct perf_evsel *evsel,

				       const void *arg),

			   const void *arg)

{

	struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;

	struct perf_evsel *last = NULL;

	int err;



	if (evlist->nr_entries > 0)

		last = perf_evlist__last(evlist);



	do {

		if (last == NULL || last->attr.type != PERF_TYPE_TRACEPOINT) {

		err = (*func)(last, arg);

		if (err)

			return -1;

		if (!last)

			return 0;



		if (last->node.prev == &evlist->entries)

			return 0;

		last = list_entry(last->node.prev, struct perf_evsel, node);

	} while (!last->cmdline_group_boundary);



	return 0;

}



static int set_filter(struct perf_evsel *evsel, const void *arg)

{

	const char *str = arg;



	if (evsel == NULL || evsel->attr.type != PERF_TYPE_TRACEPOINT) {

		fprintf(stderr,

			"--filter option should follow a -e tracepoint option\n");

		return -1;

	}



		if (perf_evsel__set_filter(last, str) < 0) {

	if (perf_evsel__append_filter(evsel, "&&", str) < 0) {

		fprintf(stderr,

			"not enough memory to hold filter string\n");

		return -1;

	}



		if (last->node.prev == &evlist->entries)

	return 0;

		last = list_entry(last->node.prev, struct perf_evsel, node);

	} while (!last->cmdline_group_boundary);

}



int parse_filter(const struct option *opt, const char *str,

		 int unset __maybe_unused)

{

	struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;



	return foreach_evsel_in_last_glob(evlist, set_filter,

					  (const void *)str);

}



static int add_exclude_perf_filter(struct perf_evsel *evsel,

				   const void *arg __maybe_unused)

{

	char new_filter[64];



	if (evsel == NULL || evsel->attr.type != PERF_TYPE_TRACEPOINT) {

		fprintf(stderr,

			"--exclude-perf option should follow a -e tracepoint option\n");

		return -1;

	}



	snprintf(new_filter, sizeof(new_filter), "common_pid != %d", getpid());



	if (perf_evsel__append_filter(evsel, "&&", new_filter) < 0) {

		fprintf(stderr,

			"not enough memory to hold filter string\n");

		return -1;

	}



	return 0;

}



int exclude_perf(const struct option *opt,

		 const char *arg __maybe_unused,

		 int unset __maybe_unused)

{

	struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;



	return foreach_evsel_in_last_glob(evlist, add_exclude_perf_filter,

					  NULL);

}



static const char * const event_type_descriptors[] = {

	"Hardware event",

	"Software event",

tools/perf/util/parse-events.h

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ extern int parse_events(struct perf_evlist *evlist, const char *str, 
			struct parse_events_error *error);

extern int parse_events_terms(struct list_head *terms, const char *str);

extern int parse_filter(const struct option *opt, const char *str, int unset);

extern int exclude_perf(const struct option *opt, const char *arg, int unset);



#define EVENTS_HELP_MAX (128*1024)