lkml.org 
[lkml]   [2010]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH 2/2] perf stat: Use event group to simulate PMI on PMI-less hardware counter
From
Date
On Wed, 2010-11-10 at 14:15 +0800, Lin Ming wrote:
> Some hardware counters(for example, Intel RAPL) can't generate interrupt
> when overflow. So we need to simulate the interrupt to periodically
> record the counter values. Otherwise, the counter may overflow and the
> wrong value is read.
>
> This patch uses event group to simulate PMI as suggested by Peter
> Zijlstra, http://marc.info/?l=linux-kernel&m=128220854801819&w=2
>
> create_group_counters() will create a group with 2 events, one hrtimer
> based event as the group leader, and the other event to count. The
> hrtimer is fired periodically, so the sibling event can record its
> counter value periodically as well.

I'm terribly confused here....
- you introduce perf_event_attr:pmi_simulate, but then you never
implement it -- nor do we need it afaict.


- you use grouped counters for perf-stat, perf-stat doesn't use
sampling so I don't see a need to group events to simulate the PMI.




\
 
 \ /
  Last update: 2010-11-10 13:25    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site