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perf record: Create events initially disabled and enable after init

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perf-record currently creates events enabled. When doing a system wide
collection (-a arg) this causes data collection for perf's
initialization activities -- eg., perf_event__synthesize_threads().

For some events (e.g., context switch S/W event or tracepoints like
syscalls) perf's initialization causes a lot of events to be captured
frequently generating "Check IO/CPU overload!" warnings on larger
systems (e.g., 2 socket, quad core, hyperthreading).

perf's initialization phase can be skipped by creating events
disabled and then enabling them once the initialization is done.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1314289075-14706-1-git-send-email-dsahern@gmail.com
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
David Ahern
2011-08-25 10:17:55 -06:00
committed by Arnaldo Carvalho de Melo
parent 694bf407b0
commit 764e16a30a
3 changed files with 17 additions and 0 deletions
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13
tools/perf/util/evlist.c
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@@ -113,6 +113,19 @@ void perf_evlist__disable(struct perf_evlist *evlist)
}
}
void perf_evlist__enable(struct perf_evlist *evlist)
{
int cpu, thread;
struct perf_evsel *pos;
for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
list_for_each_entry(pos, &evlist->entries, node) {
for (thread = 0; thread < evlist->threads->nr; thread++)
ioctl(FD(pos, cpu, thread), PERF_EVENT_IOC_ENABLE);
}
}
}
int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
{
int nfds = evlist->cpus->nr * evlist->threads->nr * evlist->nr_entries;