On Wed, 2010-03-10 at 22:26 -0800, eran...@google.com wrote: > This patch is an optimization in perf_event_task_sched_in() to avoid > scheduling > the events twice in a row. Without it, the perf_disable()/perf_enable() pair > is invoked twice, thereby pinned events counts while scheduling flexible > events > and we go throuh hw_perf_enable() twice. By encapsulating, the whole sequence > into perf_disable()/perf_enable() we ensure, hw_perf_enable() is going to be > invoked only once because of the refcount protection.
Agreed, this makes perfect sense. Acked-by: Peter Zijlstra <a.p.zijls...@chello.nl> > Signed-off-by: Stephane Eranian <eran...@google.com> > -- > perf_event.c | 4 ++++ > 1 file changed, 4 insertions(+) > > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -1382,6 +1382,8 @@ void perf_event_task_sched_in(struct task_struct *task) > if (cpuctx->task_ctx == ctx) > return; > > + perf_disable(); > + > /* > * We want to keep the following priority order: > * cpu pinned (that don't need to move), task pinned, > @@ -1394,6 +1396,8 @@ void perf_event_task_sched_in(struct task_struct *task) > ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE); > > cpuctx->task_ctx = ctx; > + > + perf_enable(); > } > > #define MAX_INTERRUPTS (~0ULL) ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
