From: Peter Zijlstra Date: Wed, 16 Dec 2009 16:55:54 +0000 (+0100) Subject: perf events: Allow per-task-per-cpu counters X-Git-Tag: firefly_0821_release~9833^2~3628^2~2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f4c4176f21533e22bcc292030da72bcfa105f5b8;p=firefly-linux-kernel-4.4.55.git perf events: Allow per-task-per-cpu counters In order to allow for per-task-per-cpu counters, useful for scalability when profiling task hierarchies, we allow installing events with event->cpu != -1 in task contexts. __perf_event_sched_in() already skips events where ->cpu mis-matches the current cpu, fix up __perf_install_in_context() and __perf_event_enable() to also respect this filter. This does lead to vary hard to interpret enabled/running times for such counters, but I don't see a simple solution for that. Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: fweisbec@gmail.com Cc: Paul Mackerras LKML-Reference: <20091216165904.831451147@chello.nl> Signed-off-by: Ingo Molnar --- diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 0dd8e5d02c66..2e0aaa34fc7e 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -782,6 +782,9 @@ static void __perf_install_in_context(void *info) add_event_to_ctx(event, ctx); + if (event->cpu != -1 && event->cpu != smp_processor_id()) + goto unlock; + /* * Don't put the event on if it is disabled or if * it is in a group and the group isn't on. @@ -925,6 +928,9 @@ static void __perf_event_enable(void *info) goto unlock; __perf_event_mark_enabled(event, ctx); + if (event->cpu != -1 && event->cpu != smp_processor_id()) + goto unlock; + /* * If the event is in a group and isn't the group leader, * then don't put it on unless the group is on. @@ -1595,10 +1601,7 @@ static struct perf_event_context *find_get_context(pid_t pid, int cpu) unsigned long flags; int err; - /* - * If cpu is not a wildcard then this is a percpu event: - */ - if (cpu != -1) { + if (pid == -1 && cpu != -1) { /* Must be root to operate on a CPU event: */ if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES);