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SubjectRe: [PATCH 1/7] perf bench: Add build-id injection benchmark
On Wed, Sep 23, 2020 at 1:05 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Sometimes I can see perf record piped with perf inject take long time
> processing build-id. So add inject-build-id benchmark to the
> internals benchmark suite to measure its overhead regularly.
>
> It runs perf inject command internally and feeds the given number of
> synthesized events (MMAP2 + SAMPLE basically).
>
> Usage: perf bench internals inject-build-id <options>
>
> -i, --iterations <n> Number of iterations used to compute average (default: 100)
> -m, --nr-mmaps <n> Number of mmap events for each iteration (default: 100)
> -n, --nr-samples <n> Number of sample events per mmap event (default: 100)
> -v, --verbose be more verbose (show iteration count, DSO name, etc)
>
> By default, it measures average processing time of 100 MMAP2 events
> and 10000 SAMPLE events. Below is a result on my laptop.
>
> $ perf bench internals inject-build-id
> # Running 'internals/inject-build-id' benchmark:
> Average build-id injection took: 22.997 msec (+- 0.067 msec)
> Average time per event: 2.255 usec (+- 0.007 usec)

This is great! Some suggestions below.

> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/bench/Build | 1 +
> tools/perf/bench/bench.h | 1 +
> tools/perf/bench/inject-buildid.c | 417 ++++++++++++++++++++++++++++++
> tools/perf/builtin-bench.c | 1 +
> tools/perf/builtin-inject.c | 9 +-
> tools/perf/util/build-id.h | 4 +
> 6 files changed, 428 insertions(+), 5 deletions(-)
> create mode 100644 tools/perf/bench/inject-buildid.c
>
> diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build
> index dd68a40a790c..8b52591338d6 100644
> --- a/tools/perf/bench/Build
> +++ b/tools/perf/bench/Build
> @@ -12,6 +12,7 @@ perf-y += epoll-ctl.o
> perf-y += synthesize.o
> perf-y += kallsyms-parse.o
> perf-y += find-bit-bench.o
> +perf-y += inject-buildid.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 2804812d4154..eac36afab2b3 100644
> --- a/tools/perf/bench/bench.h
> +++ b/tools/perf/bench/bench.h
> @@ -47,6 +47,7 @@ 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);
> int bench_kallsyms_parse(int argc, const char **argv);
> +int bench_inject_build_id(int argc, const char **argv);
>
> #define BENCH_FORMAT_DEFAULT_STR "default"
> #define BENCH_FORMAT_DEFAULT 0
> diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
> new file mode 100644
> index 000000000000..e5144a85d689
> --- /dev/null
> +++ b/tools/perf/bench/inject-buildid.c
> @@ -0,0 +1,417 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <stdlib.h>
> +#include <stddef.h>
> +#include <ftw.h>
> +#include <fcntl.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <sys/wait.h>
> +#include <linux/kernel.h>
> +#include <linux/time64.h>
> +#include <linux/list.h>
> +#include <linux/err.h>
> +#include <internal/lib.h>
> +#include <subcmd/parse-options.h>
> +
> +#include "bench.h"
> +#include "util/data.h"
> +#include "util/stat.h"
> +#include "util/debug.h"
> +#include "util/event.h"
> +#include "util/symbol.h"
> +#include "util/session.h"
> +#include "util/build-id.h"
> +#include "util/synthetic-events.h"
> +
> +#define MMAP_DEV_MAJOR 8
> +
> +static unsigned int iterations = 100;
> +static unsigned int nr_mmaps = 100;
> +static unsigned int nr_samples = 100; /* samples per mmap */
> +
> +static u64 bench_sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_TID;
> +static u16 bench_id_hdr_size = 8; /* only for pid/tid */
> +
> +struct bench_data {
> + int pid;
> + int input_pipe[2];
> + int output_pipe[2];
> +};
> +
> +struct bench_dso {
> + struct list_head list;
> + char *name;
> + int ino;
> +};
> +
> +static int nr_dsos;
> +static LIST_HEAD(dso_list);
> +
> +extern int cmd_inject(int argc, const char *argv[]);
> +
> +static const struct option options[] = {
> + OPT_UINTEGER('i', "iterations", &iterations,
> + "Number of iterations used to compute average (default: 100)"),
> + OPT_UINTEGER('m', "nr-mmaps", &nr_mmaps,
> + "Number of mmap events for each iteration (default: 100)"),
> + OPT_UINTEGER('n', "nr-samples", &nr_samples,
> + "Number of sample events per mmap event (default: 100)"),
> + OPT_INCR('v', "verbose", &verbose,
> + "be more verbose (show iteration count, DSO name, etc)"),
> + OPT_END()
> +};
> +
> +static const char *const bench_usage[] = {
> + "perf bench internals inject-build-id <options>",
> + NULL
> +};
> +

Perhaps a comment:
/* Helper for collect_dso that adds the given file as a dso to
dso_list if it contains a buildid. Stops after 4 such dsos.*/

> +static int add_dso(const char *fpath, const struct stat *sb __maybe_unused,
> + int typeflag, struct FTW *ftwbuf __maybe_unused)
> +{
> + struct bench_dso *dso;
> + unsigned char build_id[BUILD_ID_SIZE];
> +
> + if (typeflag == FTW_D || typeflag == FTW_SL) {
> + return 0;
> + }
> +
> + if (filename__read_build_id(fpath, build_id, BUILD_ID_SIZE) < 0)
> + return 0;
> +
> + dso = malloc(sizeof(*dso));
> + if (dso == NULL)
> + return -1;
> +
> + dso->name = realpath(fpath, NULL);
> + if (dso->name == NULL) {
> + free(dso);
> + return -1;
> + }
> +
> + dso->ino = nr_dsos++;
> + list_add(&dso->list, &dso_list);
> + pr_debug2(" Adding DSO: %s\n", fpath);
> +
> + /* stop if we collected 4x DSOs than needed */
> + if ((unsigned)nr_dsos > 4 * nr_mmaps)
> + return 1;
> +
> + return 0;
> +}
> +
> +static void collect_dso(void)
> +{
> + if (nftw("/usr/lib/", add_dso, 10, FTW_PHYS) < 0)
> + return;
> +
> + pr_debug(" Collected %d DSOs\n", nr_dsos);

Should this fail if the count isn't 4?

> +}
> +
> +static void release_dso(void)
> +{
> + struct bench_dso *dso;
> +
> + while (!list_empty(&dso_list)) {
> + dso = list_first_entry(&dso_list, struct bench_dso, list);
> + list_del(&dso->list);
> + free(dso->name);
> + free(dso);
> + }
> +}
> +

Perhaps a comment and move next to synthesize_mmap.
/* Fake address used by mmap events. */

> +static u64 dso_map_addr(struct bench_dso *dso)
> +{
> + return 0x400000ULL + dso->ino * 8192ULL;
> +}
> +
> +static u32 synthesize_attr(struct bench_data *data)
> +{
> + union perf_event event;
> +
> + memset(&event, 0, sizeof(event.attr) + sizeof(u64));
> +
> + event.header.type = PERF_RECORD_HEADER_ATTR;
> + event.header.size = sizeof(event.attr) + sizeof(u64);
> +
> + event.attr.attr.type = PERF_TYPE_SOFTWARE;
> + event.attr.attr.config = PERF_COUNT_SW_TASK_CLOCK;
> + event.attr.attr.exclude_kernel = 1;
> + event.attr.attr.sample_id_all = 1;
> + event.attr.attr.sample_type = bench_sample_type;
> +
> + return writen(data->input_pipe[1], &event, event.header.size);
> +}
> +
> +static u32 synthesize_fork(struct bench_data *data)
> +{
> + union perf_event event;
> +
> + memset(&event, 0, sizeof(event.fork) + bench_id_hdr_size);
> +
> + event.header.type = PERF_RECORD_FORK;
> + event.header.misc = PERF_RECORD_MISC_FORK_EXEC;
> + event.header.size = sizeof(event.fork) + bench_id_hdr_size;
> +
> + event.fork.ppid = 1;
> + event.fork.ptid = 1;
> + event.fork.pid = data->pid;
> + event.fork.tid = data->pid;
> +
> + return writen(data->input_pipe[1], &event, event.header.size);
> +}
> +
> +static u32 synthesize_mmap(struct bench_data *data, struct bench_dso *dso)
> +{
> + union perf_event event;
> + size_t len = offsetof(struct perf_record_mmap2, filename);
> +
> + len += roundup(strlen(dso->name) + 1, 8) + bench_id_hdr_size;
> +
> + memset(&event, 0, min(len, sizeof(event.mmap2)));
> +
> + event.header.type = PERF_RECORD_MMAP2;
> + event.header.misc = PERF_RECORD_MISC_USER;
> + event.header.size = len;
> +
> + event.mmap2.pid = data->pid;
> + event.mmap2.tid = data->pid;
> + event.mmap2.maj = MMAP_DEV_MAJOR;
> + event.mmap2.ino = dso->ino;
> +
> + strcpy(event.mmap2.filename, dso->name);
> +
> + event.mmap2.start = dso_map_addr(dso);
> + event.mmap2.len = 4096;
> + event.mmap2.prot = PROT_EXEC;
> +
> + if (len > sizeof(event.mmap2)) {
> + /* write mmap2 event first */
> + writen(data->input_pipe[1], &event, len - bench_id_hdr_size);
> + /* write zero-filled sample id header */
> + memset(&event, 0, bench_id_hdr_size);
> + writen(data->input_pipe[1], &event, bench_id_hdr_size);
> + } else {
> + writen(data->input_pipe[1], &event, len);
> + }
> + return len;
> +}
> +
> +static u32 synthesize_sample(struct bench_data *data, struct bench_dso *dso)
> +{
> + union perf_event event;
> + struct perf_sample sample = {
> + .tid = data->pid,
> + .pid = data->pid,
> + .ip = dso_map_addr(dso),
> + };
> +
> + event.header.type = PERF_RECORD_SAMPLE;
> + event.header.misc = PERF_RECORD_MISC_USER;
> + event.header.size = perf_event__sample_event_size(&sample, bench_sample_type, 0);
> +
> + perf_event__synthesize_sample(&event, bench_sample_type, 0, &sample);
> +
> + return writen(data->input_pipe[1], &event, event.header.size);
> +}
> +
> +static void sigpipe_handler(int sig __maybe_unused)
> +{
> + /* child exited */
> +}
> +
> +static int setup_injection(struct bench_data *data)
> +{
> + int ready_pipe[2];
> + int dev_null_fd;
> + char buf;
> +
> + if (pipe(ready_pipe) < 0)
> + return -1;
> +
> + if (pipe(data->input_pipe) < 0)
> + return -1;
> +
> + if (pipe(data->output_pipe) < 0)
> + return -1;
> +
> + data->pid = fork();
> + if (data->pid < 0)
> + return -1;
> +
> + if (data->pid == 0) {
> + const char **inject_argv;
> +
> + close(data->input_pipe[1]);
> + close(data->output_pipe[0]);
> + close(ready_pipe[0]);
> +
> + dup2(data->input_pipe[0], STDIN_FILENO);
> + close(data->input_pipe[0]);
> + dup2(data->output_pipe[1], STDOUT_FILENO);
> + close(data->output_pipe[1]);
> +
> + dev_null_fd = open("/dev/null", O_WRONLY);
> + if (dev_null_fd < 0)
> + exit(1);
> +
> + dup2(dev_null_fd, STDERR_FILENO);
> +
> + inject_argv = calloc(3, sizeof(*inject_argv));
> + if (inject_argv == NULL)
> + exit(1);
> +
> + inject_argv[0] = strdup("inject");
> + inject_argv[1] = strdup("-b");
> +
> + /* signal that we're ready to go */
> + close(ready_pipe[1]);
> +
> + cmd_inject(2, inject_argv);
> +
> + exit(0);
> + }
> +
> + signal(SIGPIPE, sigpipe_handler);
> +
> + close(ready_pipe[1]);
> + close(data->input_pipe[0]);
> + close(data->output_pipe[1]);
> +
> + /* wait for child ready */
> + if (read(ready_pipe[0], &buf, 1) < 0)
> + return -1;
> + close(ready_pipe[0]);
> +
> + return 0;
> +}

This feels like generic scaffolding that could be shared by other perf
command benchmarks.

> +
> +static int inject_build_id(struct bench_data *data)
> +{
> + int flag, status;
> + unsigned int i, k;
> + char buf[8192];
> + u64 nread = 0;
> + u64 len = nr_mmaps / 2 * sizeof(struct perf_record_header_build_id);
> +
> + flag = fcntl(data->output_pipe[0], F_GETFL, 0);
> + if (fcntl(data->output_pipe[0], F_SETFL, flag | O_NONBLOCK) < 0)
> + return -1;
> +
> + /* this makes the child to run */
> + if (perf_header__write_pipe(data->input_pipe[1]) < 0)
> + return -1;
> +
> + len += synthesize_attr(data);
> + len += synthesize_fork(data);
> +
> + for (i = 0; i < nr_mmaps; i++) {
> + struct bench_dso *dso;
> + int idx = rand() % (nr_dsos - 1);
> +
> + dso = list_first_entry(&dso_list, struct bench_dso, list);
> + while (idx--)
> + dso = list_next_entry(dso, list);
> +
> + pr_debug(" [%2d] injecting: %s\n", i+1, dso->name);
> + len += synthesize_mmap(data, dso);
> +
> + for (k = 0; k < nr_samples; k++)
> + len += synthesize_sample(data, dso);
> +
> + /* read out data from child */
> + while (true) {
> + int n;
> +
> + n = read(data->output_pipe[0], buf, sizeof(buf));
> + if (n <= 0)
> + break;
> + nread += n;
> + }
> + }
> +
> + /* wait to read data at least as we wrote + some build-ids */
> + while (nread < len) {
> + int n;
> +
> + n = read(data->output_pipe[0], buf, sizeof(buf));
> + if (n < 0)
> + break;
> + nread += n;
> + }
> + close(data->input_pipe[1]);
> + close(data->output_pipe[0]);
> +
> + wait(&status);
> + pr_debug(" Child %d exited with %d\n", data->pid, status);
> +
> + return 0;
> +}
>

Perhaps we can read the highwater mark (VmHWM) from /proc/[pid]/status
as this would capture cases like buildid injection doing unnecessary
symbol generation.

> +static int do_inject_loop(struct bench_data *data)
> +{
> + unsigned int i;
> + struct stats time_stats;
> + double time_average, time_stddev;
> +
> + srand(time(NULL));
> + init_stats(&time_stats);
> + symbol__init(NULL);
> +
> + collect_dso();
> + if (nr_dsos == 0) {
> + printf(" Cannot collect DSOs for injection\n");
> + return -1;
> + }
> +
> + for (i = 0; i < iterations; i++) {
> + struct timeval start, end, diff;
> + u64 runtime_us;
> +
> + pr_debug(" Iteration #%d\n", i+1);
> +
> + if (setup_injection(data) < 0) {
> + printf(" Build-id injection setup failed\n");
> + break;
> + }
> +
> + gettimeofday(&start, NULL);
> + if (inject_build_id(data) < 0) {
> + printf(" Build-id injection failed\n");
> + break;
> + }
> +
> + gettimeofday(&end, NULL);
> + timersub(&end, &start, &diff);
> + runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
> + update_stats(&time_stats, runtime_us);
> + }
> +
> + time_average = avg_stats(&time_stats) / USEC_PER_MSEC;
> + time_stddev = stddev_stats(&time_stats) / USEC_PER_MSEC;
> + printf(" Average build-id injection took: %.3f msec (+- %.3f msec)\n",
> + time_average, time_stddev);
> +
> + /* each iteration, it processes MMAP2 + BUILD_ID + nr_samples * SAMPLE */
> + time_average = avg_stats(&time_stats) / (nr_mmaps * (nr_samples + 2));
> + time_stddev = stddev_stats(&time_stats) / (nr_mmaps * (nr_samples + 2));
> + printf(" Average time per event: %.3f usec (+- %.3f usec)\n",
> + time_average, time_stddev);
> + release_dso();
> + return 0;
> +}
> +
> +int bench_inject_build_id(int argc, const char **argv)
> +{
> + struct bench_data data;
> +
> + argc = parse_options(argc, argv, options, bench_usage, 0);
> + if (argc) {
> + usage_with_options(bench_usage, options);
> + exit(EXIT_FAILURE);
> + }
> +
> + return do_inject_loop(&data);
> +}
> +
> diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
> index 4f176039fc8f..62a7b7420a44 100644
> --- a/tools/perf/builtin-bench.c
> +++ b/tools/perf/builtin-bench.c
> @@ -87,6 +87,7 @@ static struct bench epoll_benchmarks[] = {
> static struct bench internals_benchmarks[] = {
> { "synthesize", "Benchmark perf event synthesis", bench_synthesize },
> { "kallsyms-parse", "Benchmark kallsyms parsing", bench_kallsyms_parse },
> + { "inject-build-id", "Benchmark build-id injection", bench_inject_build_id },
> { NULL, NULL, NULL }
> };
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 6d2f410d773a..e4d78f11494e 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -441,11 +441,10 @@ static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
> return 0;
> }
>
> -static int perf_event__inject_buildid(struct perf_tool *tool,
> - union perf_event *event,
> - struct perf_sample *sample,
> - struct evsel *evsel __maybe_unused,
> - struct machine *machine)
> +int perf_event__inject_buildid(struct perf_tool *tool, union perf_event *event,
> + struct perf_sample *sample,
> + struct evsel *evsel __maybe_unused,
> + struct machine *machine)
> {
> struct addr_location al;
> struct thread *thread;
> diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
> index aad419bb165c..949f7e54c9cb 100644
> --- a/tools/perf/util/build-id.h
> +++ b/tools/perf/util/build-id.h
> @@ -29,6 +29,10 @@ int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event,
>
> int dsos__hit_all(struct perf_session *session);
>
> +int perf_event__inject_buildid(struct perf_tool *tool, union perf_event *event,
> + struct perf_sample *sample, struct evsel *evsel,
> + struct machine *machine);
> +
> bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
> int perf_session__write_buildid_table(struct perf_session *session,
> struct feat_fd *fd);
> --
> 2.28.0.681.g6f77f65b4e-goog
>

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