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Date: Tue, 15 Jul 2014 21:05:09 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
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
On 15/07/2014 6:03 p.m., Arnaldo Carvalho de Melo wrote:
> 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...
pollfd is not a 2-dimensional array. It is just a 1-dimensional array.
So it just needs to be the right length.
>
>> 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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