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SubjectRe: [PATCH v2 26/48] perf evsel: Derive CPUs and threads in alloc_counts
On Wed, Dec 22, 2021 at 11:47 PM Ian Rogers <irogers@google.com> wrote:
>
> Passing the number of CPUs and threads allows for an evsel's counts to
> be mismatched to its cpu map. To avoid this always derive the counts
> size from the cpu map. Change openaat-syscall-all-cpus to set the cpus

s/openaat/openat/

> to allow for this to work.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/tests/openat-syscall-all-cpus.c | 10 +---------
> tools/perf/util/counts.c | 8 ++++++--
> tools/perf/util/counts.h | 2 +-
> tools/perf/util/evsel.c | 2 +-
> tools/perf/util/stat.c | 13 ++++++-------
> 5 files changed, 15 insertions(+), 20 deletions(-)
>
> diff --git a/tools/perf/tests/openat-syscall-all-cpus.c b/tools/perf/tests/openat-syscall-all-cpus.c
> index cd3dd463783f..544db0839b3b 100644
> --- a/tools/perf/tests/openat-syscall-all-cpus.c
> +++ b/tools/perf/tests/openat-syscall-all-cpus.c
> @@ -85,15 +85,7 @@ static int test__openat_syscall_event_on_all_cpus(struct test_suite *test __mayb
> CPU_CLR(cpus->map[cpu], &cpu_set);
> }
>
> - /*
> - * Here we need to explicitly preallocate the counts, as if
> - * we use the auto allocation it will allocate just for 1 cpu,
> - * as we start by cpu 0.
> - */
> - if (evsel__alloc_counts(evsel, cpus->nr, 1) < 0) {
> - pr_debug("evsel__alloc_counts(ncpus=%d)\n", cpus->nr);
> - goto out_close_fd;
> - }
> + evsel->core.cpus = perf_cpu_map__get(cpus);

I was about to write that you need to call
evsel__alloc_counts() after this. But it seems
evsel__read_on_cpu() can do the job later.
So I'm fine with this. :)

Thanks,
Namhyung

>
> err = 0;
>
> diff --git a/tools/perf/util/counts.c b/tools/perf/util/counts.c
> index 582f3aeaf5e4..2b81707b9dba 100644
> --- a/tools/perf/util/counts.c
> +++ b/tools/perf/util/counts.c
> @@ -4,6 +4,7 @@
> #include <string.h>
> #include "evsel.h"
> #include "counts.h"
> +#include <perf/threadmap.h>
> #include <linux/zalloc.h>
>
> struct perf_counts *perf_counts__new(int ncpus, int nthreads)
> @@ -55,9 +56,12 @@ void evsel__reset_counts(struct evsel *evsel)
> perf_counts__reset(evsel->counts);
> }
>
> -int evsel__alloc_counts(struct evsel *evsel, int ncpus, int nthreads)
> +int evsel__alloc_counts(struct evsel *evsel)
> {
> - evsel->counts = perf_counts__new(ncpus, nthreads);
> + struct perf_cpu_map *cpus = evsel__cpus(evsel);
> + int nthreads = perf_thread_map__nr(evsel->core.threads);
> +
> + evsel->counts = perf_counts__new(cpus ? cpus->nr : 1, nthreads);
> return evsel->counts != NULL ? 0 : -ENOMEM;
> }
>
> diff --git a/tools/perf/util/counts.h b/tools/perf/util/counts.h
> index 7ff36bf6d644..3e275e9c60d1 100644
> --- a/tools/perf/util/counts.h
> +++ b/tools/perf/util/counts.h
> @@ -40,7 +40,7 @@ void perf_counts__delete(struct perf_counts *counts);
> void perf_counts__reset(struct perf_counts *counts);
>
> void evsel__reset_counts(struct evsel *evsel);
> -int evsel__alloc_counts(struct evsel *evsel, int ncpus, int nthreads);
> +int evsel__alloc_counts(struct evsel *evsel);
> void evsel__free_counts(struct evsel *evsel);
>
> #endif /* __PERF_COUNTS_H */
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 656c30b988ce..6c9af21776e6 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1578,7 +1578,7 @@ int __evsel__read_on_cpu(struct evsel *evsel, int cpu, int thread, bool scale)
> if (FD(evsel, cpu, thread) < 0)
> return -EINVAL;
>
> - if (evsel->counts == NULL && evsel__alloc_counts(evsel, cpu + 1, thread + 1) < 0)
> + if (evsel->counts == NULL && evsel__alloc_counts(evsel) < 0)
> return -ENOMEM;
>
> if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) <= 0)
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index c69b221f5e3e..995cb5003133 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -152,11 +152,13 @@ static void evsel__free_stat_priv(struct evsel *evsel)
> zfree(&evsel->stats);
> }
>
> -static int evsel__alloc_prev_raw_counts(struct evsel *evsel, int ncpus, int nthreads)
> +static int evsel__alloc_prev_raw_counts(struct evsel *evsel)
> {
> + int cpu_map_nr = evsel__nr_cpus(evsel);
> + int nthreads = perf_thread_map__nr(evsel->core.threads);
> struct perf_counts *counts;
>
> - counts = perf_counts__new(ncpus, nthreads);
> + counts = perf_counts__new(cpu_map_nr, nthreads);
> if (counts)
> evsel->prev_raw_counts = counts;
>
> @@ -177,12 +179,9 @@ static void evsel__reset_prev_raw_counts(struct evsel *evsel)
>
> static int evsel__alloc_stats(struct evsel *evsel, bool alloc_raw)
> {
> - int ncpus = evsel__nr_cpus(evsel);
> - int nthreads = perf_thread_map__nr(evsel->core.threads);
> -
> if (evsel__alloc_stat_priv(evsel) < 0 ||
> - evsel__alloc_counts(evsel, ncpus, nthreads) < 0 ||
> - (alloc_raw && evsel__alloc_prev_raw_counts(evsel, ncpus, nthreads) < 0))
> + evsel__alloc_counts(evsel) < 0 ||
> + (alloc_raw && evsel__alloc_prev_raw_counts(evsel) < 0))
> return -ENOMEM;
>
> return 0;
> --
> 2.34.1.307.g9b7440fafd-goog
>

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