Commit 2a4b5166 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf bench: Add event synthesis benchmark 



Event synthesis may occur at the start or end (tail) of a perf command.
In system-wide mode it can scan every process in /proc, which may add
seconds of latency before event recording. Add a new benchmark that
times how long event synthesis takes with and without data synthesis.

An example execution looks like:

 $ perf bench internals synthesize
 # Running 'internals/synthesize' benchmark:
 Average synthesis took: 168.253800 usec
 Average data synthesis took: 208.104700 usec

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrey Zhizhikin <andrey.z@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200402154357.107873-2-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 1a2725f3

tools/perf/Documentation/perf-bench.txt

+8 −0
Original line number Diff line number Diff line
@@ -61,6 +61,9 @@ SUBSYSTEM 
'epoll'::

	Eventpoll (epoll) stressing benchmarks.



'internals'::

	Benchmark internal perf functionality.



'all'::

	All benchmark subsystems.
@@ -214,6 +217,11 @@ Suite for evaluating concurrent epoll_wait calls. 
*ctl*::

Suite for evaluating multiple epoll_ctl calls.



SUITES FOR 'internals'

~~~~~~~~~~~~~~~~~~~~~~

*synthesize*::

Suite for evaluating perf's event synthesis performance.



SEE ALSO

--------

linkperf:perf[1]

tools/perf/bench/Build

+1 −1
Original line number Diff line number Diff line
@@ -6,9 +6,9 @@ perf-y += futex-wake.o 
perf-y += futex-wake-parallel.o

perf-y += futex-requeue.o

perf-y += futex-lock-pi.o



perf-y += epoll-wait.o

perf-y += epoll-ctl.o

perf-y += synthesize.o



perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-lib.o

perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o

tools/perf/bench/bench.h

+1 −1
Original line number Diff line number Diff line
@@ -41,9 +41,9 @@ int bench_futex_wake_parallel(int argc, const char **argv); 
int bench_futex_requeue(int argc, const char **argv);

/* pi futexes */

int bench_futex_lock_pi(int argc, const char **argv);



int bench_epoll_wait(int argc, const char **argv);

int bench_epoll_ctl(int argc, const char **argv);

int bench_synthesize(int argc, const char **argv);



#define BENCH_FORMAT_DEFAULT_STR	"default"

#define BENCH_FORMAT_DEFAULT		0

tools/perf/bench/synthesize.c

0 → 100644
+101 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Benchmark synthesis of perf events such as at the start of a 'perf

 * record'. Synthesis is done on the current process and the 'dummy' event

 * handlers are invoked that support dump_trace but otherwise do nothing.

 *

 * Copyright 2019 Google LLC.

 */

#include <stdio.h>

#include "bench.h"

#include "../util/debug.h"

#include "../util/session.h"

#include "../util/synthetic-events.h"

#include "../util/target.h"

#include "../util/thread_map.h"

#include "../util/tool.h"

#include <linux/err.h>

#include <linux/time64.h>

#include <subcmd/parse-options.h>



static unsigned int iterations = 10000;



static const struct option options[] = {

	OPT_UINTEGER('i', "iterations", &iterations,

		"Number of iterations used to compute average"),

	OPT_END()

};



static const char *const usage[] = {

	"perf bench internals synthesize <options>",

	NULL

};





static int do_synthesize(struct perf_session *session,

			struct perf_thread_map *threads,

			struct target *target, bool data_mmap)

{

	const unsigned int nr_threads_synthesize = 1;

	struct timeval start, end, diff;

	u64 runtime_us;

	unsigned int i;

	double average;

	int err;



	gettimeofday(&start, NULL);

	for (i = 0; i < iterations; i++) {

		err = machine__synthesize_threads(&session->machines.host,

						target, threads, data_mmap,

						nr_threads_synthesize);

		if (err)

			return err;

	}



	gettimeofday(&end, NULL);

	timersub(&end, &start, &diff);

	runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;

	average = (double)runtime_us/(double)iterations;

	printf("Average %ssynthesis took: %f usec\n",

		data_mmap ? "data " : "", average);

	return 0;

}



int bench_synthesize(int argc, const char **argv)

{

	struct perf_tool tool;

	struct perf_session *session;

	struct target target = {

		.pid = "self",

	};

	struct perf_thread_map *threads;

	int err;



	argc = parse_options(argc, argv, options, usage, 0);



	session = perf_session__new(NULL, false, NULL);

	if (IS_ERR(session)) {

		pr_err("Session creation failed.\n");

		return PTR_ERR(session);

	}

	threads = thread_map__new_by_pid(getpid());

	if (!threads) {

		pr_err("Thread map creation failed.\n");

		err = -ENOMEM;

		goto err_out;

	}

	perf_tool__fill_defaults(&tool);



	err = do_synthesize(session, threads, &target, false);

	if (err)

		goto err_out;



	err = do_synthesize(session, threads, &target, true);



err_out:

	if (threads)

		perf_thread_map__put(threads);



	perf_session__delete(session);

	return err;

}

tools/perf/builtin-bench.c

+6 −0
Original line number Diff line number Diff line
@@ -76,6 +76,11 @@ static struct bench epoll_benchmarks[] = { 
};

#endif // HAVE_EVENTFD



static struct bench internals_benchmarks[] = {

	{ "synthesize", "Benchmark perf event synthesis",	bench_synthesize	},

	{ NULL,		NULL,					NULL			}

};



struct collection {

	const char	*name;

	const char	*summary;
@@ -92,6 +97,7 @@ static struct collection collections[] = { 
#ifdef HAVE_EVENTFD

	{"epoll",       "Epoll stressing benchmarks",                   epoll_benchmarks        },

#endif

	{ "internals",	"Perf-internals benchmarks",			internals_benchmarks	},

	{ "all",	"All benchmarks",				NULL			},

	{ NULL,		NULL,						NULL			}

};