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

[Arnaldo Carvalho de Melo]

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@xxxxxxxxxx>
> ---
>  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