Re: [PATCH v8 03/22] perf record: Introduce thread local variable

From: Arnaldo Carvalho de Melo
Date: Wed Jun 30 2021 - 13:17:06 EST

Next message: H. Nikolaus Schaller: "Re: [PATCH] regulator: palmas: set supply_name after registering the regulator"
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In reply to: Alexey Bayduraev: "[PATCH v8 03/22] perf record: Introduce thread local variable"
Next in thread: Alexey Bayduraev: "[PATCH v8 04/22] perf record: Stop threads in the end of trace streaming"
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Em Wed, Jun 30, 2021 at 06:54:42PM +0300, Alexey Bayduraev escreveu:
> Introduce thread local variable and use it for threaded trace streaming.
> Use thread affinity mask instead or record affinity mask in affinity
> modes.
> Introduce and use evlist__ctlfd_update() function to propagate external
> control commands to global evlist object.
>
> Acked-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Acked-by: Namhyung Kim <namhyung@xxxxxxxxx>
> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@xxxxxxxxxxxxxxx>
> ---
> tools/perf/builtin-record.c | 135 ++++++++++++++++++++++++------------
> tools/perf/util/evlist.c | 16 +++++
> tools/perf/util/evlist.h | 1 +
> 3 files changed, 107 insertions(+), 45 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 11ce64b23db4..3935c0fabe01 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -110,6 +110,8 @@ struct thread_data {
> unsigned long waking;
> };
>
> +static __thread struct thread_data *thread;
> +
> struct record {
> struct perf_tool tool;
> struct record_opts opts;
> @@ -132,7 +134,6 @@ struct record {
> bool timestamp_boundary;
> struct switch_output switch_output;
> unsigned long long samples;
> - struct mmap_cpu_mask affinity_mask;
> unsigned long output_max_size; /* = 0: unlimited */
> struct thread_mask *thread_masks;
> struct thread_data *thread_data;
> @@ -567,7 +568,7 @@ static int record__pushfn(struct mmap *map, void *to, void *bf, size_t size)
> bf = map->data;
> }
>
> - rec->samples++;
> + thread->samples++;
> return record__write(rec, map, bf, size);
> }
>
> @@ -1260,16 +1261,24 @@ static struct perf_event_header finished_round_event = {
>
> static void record__adjust_affinity(struct record *rec, struct mmap *map)
> {
> + int ret = 0;

Why you set this to zero here if it is going to be used only insde the
if block?

> +
> if (rec->opts.affinity != PERF_AFFINITY_SYS &&
> - !bitmap_equal(rec->affinity_mask.bits, map->affinity_mask.bits,
> - rec->affinity_mask.nbits)) {
> - bitmap_zero(rec->affinity_mask.bits, rec->affinity_mask.nbits);
> - bitmap_or(rec->affinity_mask.bits, rec->affinity_mask.bits,
> - map->affinity_mask.bits, rec->affinity_mask.nbits);
> - sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&rec->affinity_mask),
> - (cpu_set_t *)rec->affinity_mask.bits);
> - if (verbose == 2)
> - mmap_cpu_mask__scnprintf(&rec->affinity_mask, "thread");
> + !bitmap_equal(thread->mask->affinity.bits, map->affinity_mask.bits,
> + thread->mask->affinity.nbits)) {
> + bitmap_zero(thread->mask->affinity.bits, thread->mask->affinity.nbits);
> + bitmap_or(thread->mask->affinity.bits, thread->mask->affinity.bits,
> + map->affinity_mask.bits, thread->mask->affinity.nbits);
> + ret = sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&thread->mask->affinity),
> + (cpu_set_t *)thread->mask->affinity.bits);
> + if (ret)
> + pr_err("threads[%d]: sched_setaffinity() call failed: %s\n",
> + thread->tid, strerror(errno));

Also, if record__adjust_affinity() fails by means of sched_setaffinity
not working, shouldn't we propagate this error?

> + if (verbose == 2) {
> + pr_debug("threads[%d]: addr=", thread->tid);
> + mmap_cpu_mask__scnprintf(&thread->mask->affinity, "thread");
> + pr_debug("threads[%d]: on cpu=%d\n", thread->tid, sched_getcpu());
> + }
> }
> }
>
> @@ -1310,14 +1319,17 @@ static int record__mmap_read_evlist(struct record *rec, struct evlist *evlist,
> u64 bytes_written = rec->bytes_written;
> int i;
> int rc = 0;
> - struct mmap *maps;
> + int nr_mmaps;
> + struct mmap **maps;
> int trace_fd = rec->data.file.fd;
> off_t off = 0;
>
> if (!evlist)
> return 0;
>
> - maps = overwrite ? evlist->overwrite_mmap : evlist->mmap;
> + nr_mmaps = thread->nr_mmaps;
> + maps = overwrite ? thread->overwrite_maps : thread->maps;
> +
> if (!maps)
> return 0;
>
> @@ -1327,9 +1339,9 @@ static int record__mmap_read_evlist(struct record *rec, struct evlist *evlist,
> if (record__aio_enabled(rec))
> off = record__aio_get_pos(trace_fd);
>
> - for (i = 0; i < evlist->core.nr_mmaps; i++) {
> + for (i = 0; i < nr_mmaps; i++) {
> u64 flush = 0;
> - struct mmap *map = &maps[i];
> + struct mmap *map = maps[i];
>
> if (map->core.base) {
> record__adjust_affinity(rec, map);
> @@ -1392,6 +1404,15 @@ static int record__mmap_read_all(struct record *rec, bool synch)
> return record__mmap_read_evlist(rec, rec->evlist, true, synch);
> }
>
> +static void record__thread_munmap_filtered(struct fdarray *fda, int fd,
> + void *arg __maybe_unused)
> +{
> + struct perf_mmap *map = fda->priv[fd].ptr;
> +
> + if (map)
> + perf_mmap__put(map);
> +}
> +
> static void record__init_features(struct record *rec)
> {
> struct perf_session *session = rec->session;
> @@ -1836,6 +1857,33 @@ static void record__uniquify_name(struct record *rec)
> }
> }
>
> +static int record__start_threads(struct record *rec)
> +{
> + struct thread_data *thread_data = rec->thread_data;
> +
> + thread = &thread_data[0];
> +
> + pr_debug("threads[%d]: started on cpu=%d\n", thread->tid, sched_getcpu());
> +
> + return 0;
> +}
> +
> +static int record__stop_threads(struct record *rec, unsigned long *waking)
> +{
> + int t;
> + struct thread_data *thread_data = rec->thread_data;
> +
> + for (t = 0; t < rec->nr_threads; t++) {
> + rec->samples += thread_data[t].samples;
> + *waking += thread_data[t].waking;
> + pr_debug("threads[%d]: samples=%lld, wakes=%ld, trasferred=%ld, compressed=%ld\n",
> + thread_data[t].tid, thread_data[t].samples, thread_data[t].waking,
> + rec->session->bytes_transferred, rec->session->bytes_compressed);
> + }
> +
> + return 0;
> +}
> +
> static int __cmd_record(struct record *rec, int argc, const char **argv)
> {
> int err;
> @@ -1944,7 +1992,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>
> if (record__open(rec) != 0) {
> err = -1;
> - goto out_child;
> + goto out_free_threads;
> }
> session->header.env.comp_mmap_len = session->evlist->core.mmap_len;
>
> @@ -1952,7 +2000,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> err = record__kcore_copy(&session->machines.host, data);
> if (err) {
> pr_err("ERROR: Failed to copy kcore\n");
> - goto out_child;
> + goto out_free_threads;
> }
> }
>
> @@ -1963,7 +2011,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> bpf__strerror_apply_obj_config(err, errbuf, sizeof(errbuf));
> pr_err("ERROR: Apply config to BPF failed: %s\n",
> errbuf);
> - goto out_child;
> + goto out_free_threads;
> }
>
> /*
> @@ -1981,11 +2029,11 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> if (data->is_pipe) {
> err = perf_header__write_pipe(fd);
> if (err < 0)
> - goto out_child;
> + goto out_free_threads;
> } else {
> err = perf_session__write_header(session, rec->evlist, fd, false);
> if (err < 0)
> - goto out_child;
> + goto out_free_threads;
> }
>
> err = -1;
> @@ -1993,16 +2041,16 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> && !perf_header__has_feat(&session->header, HEADER_BUILD_ID)) {
> pr_err("Couldn't generate buildids. "
> "Use --no-buildid to profile anyway.\n");
> - goto out_child;
> + goto out_free_threads;
> }
>
> err = record__setup_sb_evlist(rec);
> if (err)
> - goto out_child;
> + goto out_free_threads;
>
> err = record__synthesize(rec, false);
> if (err < 0)
> - goto out_child;
> + goto out_free_threads;
>
> if (rec->realtime_prio) {
> struct sched_param param;
> @@ -2011,10 +2059,13 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> if (sched_setscheduler(0, SCHED_FIFO, &param)) {
> pr_err("Could not set realtime priority.\n");
> err = -1;
> - goto out_child;
> + goto out_free_threads;
> }
> }
>
> + if (record__start_threads(rec))
> + goto out_free_threads;
> +
> /*
> * When perf is starting the traced process, all the events
> * (apart from group members) have enable_on_exec=1 set,
> @@ -2085,7 +2136,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> trigger_ready(&switch_output_trigger);
> perf_hooks__invoke_record_start();
> for (;;) {
> - unsigned long long hits = rec->samples;
> + unsigned long long hits = thread->samples;
>
> /*
> * rec->evlist->bkw_mmap_state is possible to be
> @@ -2154,20 +2205,24 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> alarm(rec->switch_output.time);
> }
>
> - if (hits == rec->samples) {
> + if (hits == thread->samples) {
> if (done || draining)
> break;
> - err = evlist__poll(rec->evlist, -1);
> + err = fdarray__poll(&thread->pollfd, -1);
> /*
> * Propagate error, only if there's any. Ignore positive
> * number of returned events and interrupt error.
> */
> if (err > 0 || (err < 0 && errno == EINTR))
> err = 0;
> - waking++;
> + thread->waking++;
>
> - if (evlist__filter_pollfd(rec->evlist, POLLERR | POLLHUP) == 0)
> + if (fdarray__filter(&thread->pollfd, POLLERR | POLLHUP,
> + record__thread_munmap_filtered, NULL) == 0)
> draining = true;
> +
> + evlist__ctlfd_update(rec->evlist,
> + &thread->pollfd.entries[thread->ctlfd_pos]);
> }
>
> if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {
> @@ -2220,18 +2275,20 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> goto out_child;
> }
>
> - if (!quiet)
> - fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
> -
> if (target__none(&rec->opts.target))
> record__synthesize_workload(rec, true);
>
> out_child:
> - evlist__finalize_ctlfd(rec->evlist);
> + record__stop_threads(rec, &waking);
> record__mmap_read_all(rec, true);
> +out_free_threads:
> record__free_thread_data(rec);
> + evlist__finalize_ctlfd(rec->evlist);
> record__aio_mmap_read_sync(rec);
>
> + if (!quiet)
> + fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
> +
> if (rec->session->bytes_transferred && rec->session->bytes_compressed) {
> ratio = (float)rec->session->bytes_transferred/(float)rec->session->bytes_compressed;
> session->header.env.comp_ratio = ratio + 0.5;
> @@ -3093,17 +3150,6 @@ int cmd_record(int argc, const char **argv)
>
> symbol__init(NULL);
>
> - if (rec->opts.affinity != PERF_AFFINITY_SYS) {
> - rec->affinity_mask.nbits = cpu__max_cpu();
> - rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
> - if (!rec->affinity_mask.bits) {
> - pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
> - err = -ENOMEM;
> - goto out_opts;
> - }
> - pr_debug2("thread mask[%zd]: empty\n", rec->affinity_mask.nbits);
> - }
> -
> err = record__auxtrace_init(rec);
> if (err)
> goto out;
> @@ -3241,7 +3287,6 @@ int cmd_record(int argc, const char **argv)
>
> err = __cmd_record(&record, argc, argv);
> out:
> - bitmap_free(rec->affinity_mask.bits);
> evlist__delete(rec->evlist);
> symbol__exit();
> auxtrace_record__free(rec->itr);

Can the following be moved to a separate patch?

> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 6ba9664089bd..3d555a98c037 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -2132,6 +2132,22 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
> return err;
> }
>
> +int evlist__ctlfd_update(struct evlist *evlist, struct pollfd *update)
> +{
> + int ctlfd_pos = evlist->ctl_fd.pos;
> + struct pollfd *entries = evlist->core.pollfd.entries;
> +
> + if (!evlist__ctlfd_initialized(evlist))
> + return 0;
> +
> + if (entries[ctlfd_pos].fd != update->fd ||
> + entries[ctlfd_pos].events != update->events)
> + return -1;
> +
> + entries[ctlfd_pos].revents = update->revents;
> + return 0;
> +}
> +
> struct evsel *evlist__find_evsel(struct evlist *evlist, int idx)
> {
> struct evsel *evsel;
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 2073cfa79f79..b7aa719c638d 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -358,6 +358,7 @@ void evlist__close_control(int ctl_fd, int ctl_fd_ack, bool *ctl_fd_close);
> int evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
> int evlist__finalize_ctlfd(struct evlist *evlist);
> bool evlist__ctlfd_initialized(struct evlist *evlist);
> +int evlist__ctlfd_update(struct evlist *evlist, struct pollfd *update);
> int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd);
> int evlist__ctlfd_ack(struct evlist *evlist);
>
> --
> 2.19.0
>

--

- Arnaldo

Next message: H. Nikolaus Schaller: "Re: [PATCH] regulator: palmas: set supply_name after registering the regulator"
Previous message: Bjorn Andersson: "Re: [PATCH 6/6] clk: qcom: videocc-sm8250: stop using mmcx regulator"
In reply to: Alexey Bayduraev: "[PATCH v8 03/22] perf record: Introduce thread local variable"
Next in thread: Alexey Bayduraev: "[PATCH v8 04/22] perf record: Stop threads in the end of trace streaming"
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