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Date: Tue, 15 Jul 2014 12:03:20 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...il.com>,
Paul Mackerras <paulus@...ba.org>,
Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 34/41] perf evlist: Add 'system_wide' option
Em Mon, Jul 14, 2014 at 01:02:58PM +0300, Adrian Hunter escreveu:
> Add an option to cause a selected event
> to be opened always without a pid when
> configured by perf_evsel__config().
>
> This is needed when using the sched_switch
> tracepoint to follow object code execution.
> sched_switch occurs before the task
> switch and so it cannot record it in a
> context limited to that task. Note
> that also means that sched_switch is
> useless when capturing data per-thread,
> as is the 'context-switches' software
> event for the same reason.
clever, but humm, need to be judicious when allocating things like the
pollfd, I think, more below...
... after going thru the whole patch, its not clear how pollfd usage
takes into account the fact that some of the evsels don't have
thread_map->nr entries, but just one, will continue reading...
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
> tools/perf/util/evlist.c | 45 +++++++++++++++++++++++++++++++++++++--------
> tools/perf/util/evsel.c | 31 ++++++++++++++++++++++++++-----
> tools/perf/util/evsel.h | 1 +
> 3 files changed, 64 insertions(+), 13 deletions(-)
>
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 282e83e..c295b7b 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -265,17 +265,27 @@ int perf_evlist__add_newtp(struct perf_evlist *evlist,
> return 0;
> }
>
> +static int perf_evlist__nr_threads(struct perf_evlist *evlist,
> + struct perf_evsel *evsel)
> +{
> + if (evsel->system_wide)
> + return 1;
> + else
> + return thread_map__nr(evlist->threads);
> +}
> +
> void perf_evlist__disable(struct perf_evlist *evlist)
> {
> int cpu, thread;
> struct perf_evsel *pos;
> int nr_cpus = cpu_map__nr(evlist->cpus);
> - int nr_threads = thread_map__nr(evlist->threads);
> + int nr_threads;
>
> for (cpu = 0; cpu < nr_cpus; cpu++) {
> evlist__for_each(evlist, pos) {
> if (!perf_evsel__is_group_leader(pos) || !pos->fd)
> continue;
> + nr_threads = perf_evlist__nr_threads(evlist, pos);
> for (thread = 0; thread < nr_threads; thread++)
> ioctl(FD(pos, cpu, thread),
> PERF_EVENT_IOC_DISABLE, 0);
> @@ -288,12 +298,13 @@ void perf_evlist__enable(struct perf_evlist *evlist)
> int cpu, thread;
> struct perf_evsel *pos;
> int nr_cpus = cpu_map__nr(evlist->cpus);
> - int nr_threads = thread_map__nr(evlist->threads);
> + int nr_threads;
>
> for (cpu = 0; cpu < nr_cpus; cpu++) {
> evlist__for_each(evlist, pos) {
> if (!perf_evsel__is_group_leader(pos) || !pos->fd)
> continue;
> + nr_threads = perf_evlist__nr_threads(evlist, pos);
> for (thread = 0; thread < nr_threads; thread++)
> ioctl(FD(pos, cpu, thread),
> PERF_EVENT_IOC_ENABLE, 0);
> @@ -305,12 +316,14 @@ int perf_evlist__disable_event(struct perf_evlist *evlist,
> struct perf_evsel *evsel)
> {
> int cpu, thread, err;
> + int nr_cpus = cpu_map__nr(evlist->cpus);
> + int nr_threads = perf_evlist__nr_threads(evlist, evsel);
>
> if (!evsel->fd)
> return 0;
>
> - for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
> - for (thread = 0; thread < evlist->threads->nr; thread++) {
> + for (cpu = 0; cpu < nr_cpus; cpu++) {
> + for (thread = 0; thread < nr_threads; thread++) {
> err = ioctl(FD(evsel, cpu, thread),
> PERF_EVENT_IOC_DISABLE, 0);
> if (err)
> @@ -324,12 +337,14 @@ int perf_evlist__enable_event(struct perf_evlist *evlist,
> struct perf_evsel *evsel)
> {
> int cpu, thread, err;
> + int nr_cpus = cpu_map__nr(evlist->cpus);
> + int nr_threads = perf_evlist__nr_threads(evlist, evsel);
>
> if (!evsel->fd)
> return -EINVAL;
>
> - for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
> - for (thread = 0; thread < evlist->threads->nr; thread++) {
> + for (cpu = 0; cpu < nr_cpus; cpu++) {
> + for (thread = 0; thread < nr_threads; thread++) {
> err = ioctl(FD(evsel, cpu, thread),
> PERF_EVENT_IOC_ENABLE, 0);
> if (err)
All the above seems ok, the threads (x axis) array is flat when syswide, ok.
> @@ -343,7 +358,16 @@ static int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
> {
> int nr_cpus = cpu_map__nr(evlist->cpus);
> int nr_threads = thread_map__nr(evlist->threads);
> - int nfds = nr_cpus * nr_threads * evlist->nr_entries;
> + int nfds = 0;
> + struct perf_evsel *evsel;
> +
> + list_for_each_entry(evsel, &evlist->entries, node) {
> + if (evsel->system_wide)
> + nfds += nr_cpus;
> + else
> + nfds += nr_cpus * nr_threads;
> + }
But here looks tricky, will look how the evlist->pollfd is used...
> +
> evlist->pollfd = malloc(sizeof(struct pollfd) * nfds);
> return evlist->pollfd != NULL ? 0 : -ENOMEM;
> }
> @@ -636,7 +660,12 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
> struct perf_evsel *evsel;
>
> evlist__for_each(evlist, evsel) {
> - int fd = FD(evsel, cpu, thread);
> + int fd;
> +
> + if (evsel->system_wide && thread)
> + continue;
Discard after thread 0, i.e. the first, ok.
> +
> + fd = FD(evsel, cpu, thread);
>
> if (*output == -1) {
> *output = fd;
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 90f58cd..7540b5f 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -691,6 +691,10 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
> int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
> {
> int cpu, thread;
> +
> + if (evsel->system_wide)
> + nthreads = 1;
flatten it, ok
> +
> evsel->fd = xyarray__new(ncpus, nthreads, sizeof(int));
>
> if (evsel->fd) {
> @@ -709,6 +713,9 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel, int ncpus, int nthrea
> {
> int cpu, thread;
>
> + if (evsel->system_wide)
> + nthreads = 1;
> +
Ditto.
> for (cpu = 0; cpu < ncpus; cpu++) {
> for (thread = 0; thread < nthreads; thread++) {
> int fd = FD(evsel, cpu, thread),
> @@ -739,6 +746,9 @@ int perf_evsel__enable(struct perf_evsel *evsel, int ncpus, int nthreads)
>
> int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads)
> {
> + if (evsel->system_wide)
> + nthreads = 1;
> +
> evsel->sample_id = xyarray__new(ncpus, nthreads, sizeof(struct perf_sample_id));
These are per evsel, so can be flattened when we get to it,
evlist->pollfd is per evlist, so mixes syswide with !syswide, that is why I'm scratching my head at this
point...
> if (evsel->sample_id == NULL)
> return -ENOMEM;
> @@ -783,6 +793,9 @@ void perf_evsel__close_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
> {
> int cpu, thread;
>
> + if (evsel->system_wide)
> + nthreads = 1;
> +
> for (cpu = 0; cpu < ncpus; cpu++)
> for (thread = 0; thread < nthreads; ++thread) {
> close(FD(evsel, cpu, thread));
> @@ -871,6 +884,9 @@ int __perf_evsel__read(struct perf_evsel *evsel,
> int cpu, thread;
> struct perf_counts_values *aggr = &evsel->counts->aggr, count;
>
> + if (evsel->system_wide)
> + nthreads = 1;
> +
> aggr->val = aggr->ena = aggr->run = 0;
>
> for (cpu = 0; cpu < ncpus; cpu++) {
> @@ -993,13 +1009,18 @@ static size_t perf_event_attr__fprintf(struct perf_event_attr *attr, FILE *fp)
> static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
> struct thread_map *threads)
> {
> - int cpu, thread;
> + int cpu, thread, nthreads;
> unsigned long flags = 0;
> int pid = -1, err;
> enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE;
>
> + if (evsel->system_wide)
> + nthreads = 1;
> + else
> + nthreads = threads->nr;
> +
> if (evsel->fd == NULL &&
> - perf_evsel__alloc_fd(evsel, cpus->nr, threads->nr) < 0)
> + perf_evsel__alloc_fd(evsel, cpus->nr, nthreads) < 0)
> return -ENOMEM;
>
> if (evsel->cgrp) {
> @@ -1021,10 +1042,10 @@ retry_sample_id:
>
> for (cpu = 0; cpu < cpus->nr; cpu++) {
>
> - for (thread = 0; thread < threads->nr; thread++) {
> + for (thread = 0; thread < nthreads; thread++) {
> int group_fd;
>
> - if (!evsel->cgrp)
> + if (!evsel->cgrp && !evsel->system_wide)
> pid = threads->map[thread];
>
> group_fd = get_group_fd(evsel, cpu, thread);
> @@ -1094,7 +1115,7 @@ out_close:
> close(FD(evsel, cpu, thread));
> FD(evsel, cpu, thread) = -1;
> }
> - thread = threads->nr;
> + thread = nthreads;
> } while (--cpu >= 0);
> return err;
> }
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index d7f93ce..dbb2a0d 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -85,6 +85,7 @@ struct perf_evsel {
> bool needs_swap;
> bool no_aux_samples;
> bool immediate;
> + bool system_wide;
> /* parse modifier helper */
> int exclude_GH;
> int nr_members;
> --
> 1.8.3.2
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