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SubjectRe: [RFC PATCH v1 21/37] perf evsel: move ignore_missing_thread to fallback code
Em Sat, Aug 21, 2021 at 11:19:27AM +0200, Riccardo Mancini escreveu:
> This patch moves ignore_missing_thread outside the perf_event_open loop.
> Doing so, we need to move the retry_open flag a few places higher, with
> minimal impact. Furthermore, thread need not be decreased since it won't
> get increased by the for loop (since we're jumping back inside), but we
> need to check that the nthreads decrease didn't put thread out of range.
>
> The goal is to have fallbacks handled in one place only, since in the
> future parallel code, these would be handled separately.

Thanks, looks ok, applied.

- Arnaldo


> Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
> ---
> tools/perf/util/evsel.c | 29 +++++++++++++----------------
> tools/perf/util/evsel.h | 5 +++++
> 2 files changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 916930ea31450265..a1a88607fd59efcb 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1656,7 +1656,7 @@ static int update_fds(struct evsel *evsel,
> return 0;
> }
>
> -static bool ignore_missing_thread(struct evsel *evsel,
> +bool evsel__ignore_missing_thread(struct evsel *evsel,
> int nr_cpus, int cpu,
> struct perf_thread_map *threads,
> int thread, int err)
> @@ -1993,12 +1993,15 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
>
> for (thread = 0; thread < nthreads; thread++) {
> int fd, group_fd;
> +retry_open:
> + if (thread >= nthreads)
> + break;
>
> if (!evsel->cgrp && !evsel->core.system_wide)
> pid = perf_thread_map__pid(threads, thread);
>
> group_fd = get_group_fd(evsel, cpu, thread);
> -retry_open:
> +
> test_attr__ready();
>
> fd = perf_event_open(evsel, pid, cpus->map[cpu],
> @@ -2016,20 +2019,6 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
> if (fd < 0) {
> err = -errno;
>
> - if (ignore_missing_thread(evsel, cpus->nr, cpu, threads, thread, err)) {
> - /*
> - * We just removed 1 thread, so take a step
> - * back on thread index and lower the upper
> - * nthreads limit.
> - */
> - nthreads--;
> - thread--;
> -
> - /* ... and pretend like nothing have happened. */
> - err = 0;
> - continue;
> - }
> -
> pr_debug2_peo("\nsys_perf_event_open failed, error %d\n",
> err);
> goto try_fallback;
> @@ -2069,6 +2058,14 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
> return 0;
>
> try_fallback:
> + if (evsel__ignore_missing_thread(evsel, cpus->nr, cpu, threads, thread, err)) {
> + /* We just removed 1 thread, so lower the upper nthreads limit. */
> + nthreads--;
> +
> + /* ... and pretend like nothing have happened. */
> + err = 0;
> + goto retry_open;
> + }
> /*
> * perf stat needs between 5 and 22 fds per CPU. When we run out
> * of them try to increase the limits.
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index bf9abd9a5cbf9852..661d2677a19b6248 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -293,6 +293,11 @@ bool evsel__detect_missing_features(struct evsel *evsel);
> enum rlimit_action { NO_CHANGE, SET_TO_MAX, INCREASED_MAX };
> bool evsel__increase_rlimit(enum rlimit_action *set_rlimit);
>
> +bool evsel__ignore_missing_thread(struct evsel *evsel,
> + int nr_cpus, int cpu,
> + struct perf_thread_map *threads,
> + int thread, int err);
> +
> struct perf_sample;
>
> void *evsel__rawptr(struct evsel *evsel, struct perf_sample *sample, const char *name);
> --
> 2.31.1

--

- Arnaldo

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