Re: [PATCH RFC 17/21] perf tools: Allow all_cpus to be a superset of user_requested_cpus

Ian Rogers
2022-05-03T17:41:46Z

On Fri, Apr 22, 2022 at 9:24 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> To support collection of system-wide events with user requested CPUs,
> all_cpus must be a superset of user_requested_cpus.
>
> In order to support all_cpus to be a superset of user_requested_cpus,
> all_cpus must be used instead of user_requested_cpus when dealing with CPUs
> of all events instead of CPUs of requested events.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Acked-by: Ian Rogers <irogers@google.com>

> ---
> tools/lib/perf/evlist.c | 12 ++++++------
> tools/perf/builtin-record.c | 18 ++++++++++++------
> tools/perf/util/auxtrace.c | 2 +-
> 3 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> index ad04da81c367..048b546f9444 100644
> --- a/tools/lib/perf/evlist.c
> +++ b/tools/lib/perf/evlist.c
> @@ -294,7 +294,7 @@ int perf_evlist__id_add_fd(struct perf_evlist *evlist,
>
> int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
> {
> - int nr_cpus = perf_cpu_map__nr(evlist->user_requested_cpus);
> + int nr_cpus = perf_cpu_map__nr(evlist->all_cpus);
> int nr_threads = perf_thread_map__nr(evlist->threads);
> int nfds = 0;
> struct perf_evsel *evsel;
> @@ -426,7 +426,7 @@ mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
> int idx, struct perf_mmap_param *mp, int cpu_idx,
> int thread, int *_output, int *_output_overwrite)
> {
> - struct perf_cpu evlist_cpu = perf_cpu_map__cpu(evlist->user_requested_cpus, cpu_idx);
> + struct perf_cpu evlist_cpu = perf_cpu_map__cpu(evlist->all_cpus, cpu_idx);
> struct perf_evsel *evsel;
> int revent;
>
> @@ -536,7 +536,7 @@ mmap_per_cpu(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
> struct perf_mmap_param *mp)
> {
> int nr_threads = perf_thread_map__nr(evlist->threads);
> - int nr_cpus = perf_cpu_map__nr(evlist->user_requested_cpus);
> + int nr_cpus = perf_cpu_map__nr(evlist->all_cpus);
> int cpu, thread;
>
> for (cpu = 0; cpu < nr_cpus; cpu++) {
> @@ -561,8 +561,8 @@ static int perf_evlist__nr_mmaps(struct perf_evlist *evlist)
> {
> int nr_mmaps;
>
> - nr_mmaps = perf_cpu_map__nr(evlist->user_requested_cpus);
> - if (perf_cpu_map__empty(evlist->user_requested_cpus))
> + nr_mmaps = perf_cpu_map__nr(evlist->all_cpus);
> + if (perf_cpu_map__empty(evlist->all_cpus))
> nr_mmaps = perf_thread_map__nr(evlist->threads);
>
> return nr_mmaps;
> @@ -573,7 +573,7 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist,
> struct perf_mmap_param *mp)
> {
> struct perf_evsel *evsel;
> - const struct perf_cpu_map *cpus = evlist->user_requested_cpus;
> + const struct perf_cpu_map *cpus = evlist->all_cpus;
>
> if (!ops || !ops->get || !ops->mmap)
> return -EINVAL;
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 83d2f2b5dcda..42127cfd9cc1 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -967,14 +967,20 @@ static void record__thread_data_close_pipes(struct record_thread *thread_data)
> }
> }
>
> +static bool evlst__per_thread(struct evlist *evlist)
> +{
> + return cpu_map__is_dummy(evlist->core.user_requested_cpus);
> +}
> +

This is much clearer than the previous code. Could we add a comment as
to why dummy implies per-thread? What would empty imply?

Just to note the cpu_map__is_dummy adds to the confusion on whether
dummy can appear merged into a map:
"Events associated with a pid, rather than a CPU, use a single dummy
map with an entry of -1"
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/util/cpumap.h?h=perf/core#n55
If the dummy can appear in any cpu map then we should rephrase this
and possibly turn this into a has_dummy_cpu function.

Thanks,
Ian

> static int record__thread_data_init_maps(struct record_thread *thread_data, struct evlist *evlist)
> {
> int m, tm, nr_mmaps = evlist->core.nr_mmaps;
> struct mmap *mmap = evlist->mmap;
> struct mmap *overwrite_mmap = evlist->overwrite_mmap;
> - struct perf_cpu_map *cpus = evlist->core.user_requested_cpus;
> + struct perf_cpu_map *cpus = evlist->core.all_cpus;
> + bool per_thread = evlst__per_thread(evlist);
>
> - if (cpu_map__is_dummy(cpus))
> + if (per_thread)
> thread_data->nr_mmaps = nr_mmaps;
> else
> thread_data->nr_mmaps = bitmap_weight(thread_data->mask->maps.bits,
> @@ -995,7 +1001,7 @@ static int record__thread_data_init_maps(struct record_thread *thread_data, stru
> thread_data->nr_mmaps, thread_data->maps, thread_data->overwrite_maps);
>
> for (m = 0, tm = 0; m < nr_mmaps && tm < thread_data->nr_mmaps; m++) {
> - if (cpu_map__is_dummy(cpus) ||
> + if (per_thread ||
> test_bit(cpus->map[m].cpu, thread_data->mask->maps.bits)) {
> if (thread_data->maps) {
> thread_data->maps[tm] = &mmap[m];
> @@ -1870,7 +1876,7 @@ static int record__synthesize(struct record *rec, bool tail)
> return err;
> }
>
> - err = perf_event__synthesize_cpu_map(&rec->tool, rec->evlist->core.user_requested_cpus,
> + err = perf_event__synthesize_cpu_map(&rec->tool, rec->evlist->core.all_cpus,
> process_synthesized_event, NULL);
> if (err < 0) {
> pr_err("Couldn't synthesize cpu map.\n");
> @@ -3667,12 +3673,12 @@ static int record__init_thread_default_masks(struct record *rec, struct perf_cpu
> static int record__init_thread_masks(struct record *rec)
> {
> int ret = 0;
> - struct perf_cpu_map *cpus = rec->evlist->core.user_requested_cpus;
> + struct perf_cpu_map *cpus = rec->evlist->core.all_cpus;
>
> if (!record__threads_enabled(rec))
> return record__init_thread_default_masks(rec, cpus);
>
> - if (cpu_map__is_dummy(cpus)) {
> + if (evlst__per_thread(rec->evlist)) {
> pr_err("--per-thread option is mutually exclusive to parallel streaming mode.\n");
> return -EINVAL;
> }
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index 246afe99a7fb..bac1f1eb95a7 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -181,7 +181,7 @@ void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
> mp->idx = idx;
>
> if (per_cpu) {
> - mp->cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, idx);
> + mp->cpu = perf_cpu_map__cpu(evlist->core.all_cpus, idx);
> if (evlist->core.threads)
> mp->tid = perf_thread_map__pid(evlist->core.threads, 0);
> else
> --
> 2.25.1
>