Re: [PATCH v2 1/5] perf bench: add event synthesis benchmark

Arnaldo Carvalho de Melo
2020-04-06T14:07:10Z

Em Thu, Apr 02, 2020 at 08:43:53AM -0700, Ian Rogers escreveu:
> 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.

Thanks, applied,

- Arnaldo

> 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: Ian Rogers <irogers@google.com>
> ---
> tools/perf/Documentation/perf-bench.txt | 8 ++
> tools/perf/bench/Build | 2 +-
> tools/perf/bench/bench.h | 2 +-
> tools/perf/bench/synthesize.c | 101 ++++++++++++++++++++++++
> tools/perf/builtin-bench.c | 6 ++
> 5 files changed, 117 insertions(+), 2 deletions(-)
> create mode 100644 tools/perf/bench/synthesize.c
>
> diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documentation/perf-bench.txt
> index 0921a3c67381..bad16512c48d 100644
> --- a/tools/perf/Documentation/perf-bench.txt
> +++ b/tools/perf/Documentation/perf-bench.txt
> @@ -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]
> diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build
> index e4e321b6f883..042827385c87 100644
> --- a/tools/perf/bench/Build
> +++ b/tools/perf/bench/Build
> @@ -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
> diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
> index 4aa6de1aa67d..4d669c803237 100644
> --- a/tools/perf/bench/bench.h
> +++ b/tools/perf/bench/bench.h
> @@ -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
> diff --git a/tools/perf/bench/synthesize.c b/tools/perf/bench/synthesize.c
> new file mode 100644
> index 000000000000..6291257bc9c9
> --- /dev/null
> +++ b/tools/perf/bench/synthesize.c
> @@ -0,0 +1,101 @@
> +// 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;
> +}
> diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
> index c06fe21c8613..11c79a8d85d6 100644
> --- a/tools/perf/builtin-bench.c
> +++ b/tools/perf/builtin-bench.c
> @@ -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 }
> };
> --
> 2.26.0.rc2.310.g2932bb562d-goog
>

--

- Arnaldo