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From: Peter Zijlstra <email@example.com>
To: Mark Rutland <firstname.lastname@example.org>
Cc: "email@example.com" <firstname.lastname@example.org>,
Subject: Re: [RFC][PATCH 1/3] perf: Tighten (and fix) the grouping condition
Date: Wed, 4 Feb 2015 13:59:54 +0100 [thread overview]
Message-ID: <20150204125954.GL21418@twins.programming.kicks-ass.net> (raw)
On Fri, Jan 23, 2015 at 03:22:57PM +0000, Mark Rutland wrote:
> > > It seems this would still allow you to group CPU-affine software and
> > > uncore events, which also doesn't make sense: the software events will
> > > count on a single CPU while the uncore events aren't really CPU-affine.
> > >
> > > Which isn't anything against this patch, but probably something we
> > > should tighten up too.
> > Indeed, that would need a wee bit of extra infrastructure though; as we
> > cannot currently distinguish between regular cpuctx and uncore like
> > things.
> Isn't the event->pmu->task_ctx_nr sufficient, as with how we identify
> software events?
> Or am I making some completely bogus assumptions in the diff below?
> + * System-wide (A.K.A. "uncore") events cannot be associated with a
> + * particular CPU, and hence cannot be associated with a particular
> + * task either. It's non-sensical to group them with other event types,
> + * which are CPU or task bound.
> + */
So I think we want to allow grouping software events with say uncore
events; if you start them both out on the same 'cpu'
perf_pmu_migrate_context() would move the software event along with it.
The use case is for non-sampling uncores, where if you have a software
leader you can still get a periodic samples. Clearly looking at task
state or the like is pointless, but PERF_SAMPLE_READ is useful to record
values at regular intervals into the buffer.
But yes, I think ctx_nr might just do.
next prev parent reply other threads:[~2015-02-04 13:00 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-23 12:51 [RFC][PATCH 0/3] perf fixes Peter Zijlstra
2015-01-23 12:52 ` [RFC][PATCH 1/3] perf: Tighten (and fix) the grouping condition Peter Zijlstra
2015-01-23 15:02 ` Mark Rutland
2015-01-23 15:07 ` Peter Zijlstra
2015-01-23 15:22 ` Mark Rutland
2015-02-04 12:59 ` Peter Zijlstra [this message]
2015-01-28 14:30 ` [tip:perf/urgent] " tip-bot for Peter Zijlstra
2015-01-23 12:52 ` [RFC][PATCH 2/3] perf: Add a bit of paranoia Peter Zijlstra
2015-01-26 16:26 ` Peter Zijlstra
2015-01-27 21:28 ` Vince Weaver
2015-01-29 2:16 ` Vince Weaver
2015-01-29 7:51 ` Jiri Olsa
2015-01-29 13:44 ` Peter Zijlstra
2015-02-04 14:39 ` [tip:perf/core] perf: Fix put_event() ctx lock tip-bot for Peter Zijlstra
2015-01-29 14:47 ` [RFC][PATCH 2/3] perf: Add a bit of paranoia Peter Zijlstra
2015-02-02 6:33 ` Vince Weaver
2015-02-02 15:42 ` Peter Zijlstra
2015-02-02 17:32 ` Peter Zijlstra
2015-02-04 14:51 ` Jiri Olsa
2015-02-04 16:33 ` Peter Zijlstra
2015-02-04 16:43 ` Peter Zijlstra
2015-02-04 14:39 ` [tip:perf/core] perf: Fix move_group() order tip-bot for Peter Zijlstra (Intel)
2015-02-04 14:39 ` [tip:perf/core] perf: Add a bit of paranoia tip-bot for Peter Zijlstra
2015-01-23 12:52 ` [RFC][PATCH 3/3] perf: Fix event->ctx locking Peter Zijlstra
2015-02-04 14:39 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2015-01-26 14:30 ` [RFC][PATCH 0/3] perf fixes Vince Weaver
2015-01-26 18:03 ` Vince Weaver
2015-01-26 18:34 ` Jiri Olsa
2015-01-26 18:52 ` Vince Weaver
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