LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"vincent.weaver@maine.edu" <vincent.weaver@maine.edu>,
	"eranian@gmail.com" <eranian@gmail.com>,
	"jolsa@redhat.com" <jolsa@redhat.com>,
	"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>
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)
In-Reply-To: <20150123152257.GB6091@leverpostej>

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.

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20150204125954.GL21418@twins.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=eranian@gmail.com \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=vincent.weaver@maine.edu \
    --subject='Re: [RFC][PATCH 1/3] perf: Tighten (and fix) the grouping condition' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).