lkml.org 
[lkml]   [2017]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] perf/x86/intel: fix event update for auto-reload
On Tue, Dec 19, 2017 at 11:07:09PM +0100, Peter Zijlstra wrote:
> On Tue, Dec 19, 2017 at 03:08:58PM -0500, Liang, Kan wrote:
> > > This all looks very wrong... In auto reload we should never call
> > > intel_pmu_save_and_restore() in the first place I think.
> > >
> > > Things like x86_perf_event_update() and x86_perf_event_set_period()
> > > simply _cannot_ do the right thing when we auto reload the counter.
> > >
> >
> > I think it should be OK to call it in first place.
> > For x86_perf_event_update(), the reload_times will tell if it's auto reload.
> > Both period_left and event->count are carefully recalculated for auto
> > reload.
>
> How does prev_count make sense when we've already reloaded a bunch of
> times?

We can figure it out how often there was a reload based on the PEBS index.

-Andi

\
 
 \ /
  Last update: 2017-12-19 23:11    [W:0.052 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site