Re: [PATCH V4 1/5] perf/x86/intel: Fix event update for auto-reload

[Liang, Kan]

On 2/21/2018 5:32 AM, Peter Zijlstra wrote:
> On Mon, Feb 12, 2018 at 02:20:31PM -0800, kan.liang@xxxxxxxxxxxxxxx wrote:
> > @@ -1389,8 +1456,22 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
> >   
> >   	ds->pebs_index = ds->pebs_buffer_base;
> >   
> > -	if (unlikely(base >= top))
> > +	if (unlikely(base >= top)) {
> > +		/*
> > +		 * The drain_pebs() could be called twice in a short period
> > +		 * for auto-reload event in pmu::read(). There are no
> > +		 * overflows have happened in between.
> > +		 * It needs to call intel_pmu_save_and_restart_reload() to
> > +		 * update the event->count for this case.
> > +		 */
> > +		for_each_set_bit(bit, (unsigned long *)&cpuc->pebs_enabled,
> > +				 x86_pmu.max_pebs_events) {
> > +			event = cpuc->events[bit];
> > +			if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
> > +				intel_pmu_save_and_restart_reload(event, 0);
> > +		}
> >   		return;
> > +	}
> >   
> >   	for (at = base; at < top; at += x86_pmu.pebs_record_size) {
> >   		struct pebs_record_nhm *p = at;
>
> Is there a reason you didn't do intel_pmu_drain_pebs_core() ?

Right, I forgot that the drain_pebs_core() also has auto_reload support.
Sorry for that.
I will re-send all patches.

Thanks,
Kan

> --- a/arch/x86/events/intel/ds.c
> +++ b/arch/x86/events/intel/ds.c
> @@ -1435,8 +1435,11 @@ static void intel_pmu_drain_pebs_core(st
>   		return;
>   
>   	n = top - at;
> -	if (n <= 0)
> +	if (n <= 0) {
> +		if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
> +			intel_pmu_save_and_restart_reload(event, 0);
>   		return;
> +	}
>   
>   	__intel_pmu_pebs_event(event, iregs, at, top, 0, n);
>   }