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From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	tonyj@suse.com, nelson.dsouza@intel.com
Subject: Re: [RFC][PATCH 6/8] perf/x86: Clear ->event_constraint[] on put
Date: Wed, 20 Mar 2019 13:25:14 +0100	[thread overview]
Message-ID: <20190320122514.GF6058@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CABPqkBReEzMKUDJVAUArwbzxtL5KTNRot2coW4MUOvy0qzgC-w@mail.gmail.com>

On Tue, Mar 19, 2019 at 02:50:21PM -0700, Stephane Eranian wrote:
> On Thu, Mar 14, 2019 at 6:11 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > The current code unconditionally clears cpuc->event_constraint[i]
> > before calling get_event_constraints(.idx=i). The only site that cares
> > is intel_get_event_constraints() where the c1 load will always be
> > NULL.
> >
> > However, always calling get_event_constraints() on all events is
> > wastefull, most times it will return the exact same result. Therefore
> > retain the logic in intel_get_event_constraints() and change the
> > generic code to only clear the constraint on put.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> 
> I thought there was caching of the constraint in case it was static
> (or unconstrained)

Yeah, I was under the same impression :-/

> to avoid walking the constraint table each time between invocations
> on the same group_sched_in() call. But the way the c1 vs. c2 logic
> is written I don't see it. In which case, this could be another opportunity.

Right, the next patch attempts this.

  reply	other threads:[~2019-03-20 12:25 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-14 13:01 [RFC][PATCH 0/8] perf/x86: event scheduling cleanups Peter Zijlstra
2019-03-14 13:01 ` [PATCH 1/8] perf/x86/intel: Fix memory corruption Peter Zijlstra
2019-03-15 11:29   ` [tip:perf/urgent] " tip-bot for Peter Zijlstra
2019-03-19  6:29   ` [PATCH 1/8] " Stephane Eranian
2019-03-19 11:05     ` Peter Zijlstra
2019-03-19 17:52       ` Stephane Eranian
2019-03-19 18:20         ` Peter Zijlstra
2019-03-20 20:47           ` Stephane Eranian
2019-03-20 20:52             ` Stephane Eranian
2019-03-20 22:22             ` Peter Zijlstra
2019-03-21 12:38               ` Peter Zijlstra
2019-03-21 16:45                 ` Thomas Gleixner
2019-03-21 17:10                   ` Peter Zijlstra
2019-03-21 17:17                     ` Thomas Gleixner
2019-03-21 18:20                       ` Peter Zijlstra
2019-03-21 19:42                         ` Tony Jones
2019-03-21 19:47                           ` DSouza, Nelson
2019-03-21 20:07                             ` Peter Zijlstra
2019-03-21 23:16                               ` DSouza, Nelson
2019-03-22 22:14                                 ` DSouza, Nelson
2019-03-21 17:23                   ` Stephane Eranian
2019-03-21 17:51                     ` Thomas Gleixner
2019-03-22 19:04                       ` Stephane Eranian
2019-04-03  7:32                         ` Peter Zijlstra
2019-04-03 10:40                 ` [tip:perf/urgent] perf/x86/intel: Initialize TFA MSR tip-bot for Peter Zijlstra
2019-04-03 11:30                   ` Thomas Gleixner
2019-04-03 12:23                     ` Vince Weaver
2019-03-14 13:01 ` [RFC][PATCH 2/8] perf/x86/intel: Simplify intel_tfa_commit_scheduling() Peter Zijlstra
2019-03-14 13:01 ` [RFC][PATCH 3/8] perf/x86: Simplify x86_pmu.get_constraints() interface Peter Zijlstra
2019-03-19 21:21   ` Stephane Eranian
2019-03-14 13:01 ` [RFC][PATCH 4/8] perf/x86: Remove PERF_X86_EVENT_COMMITTED Peter Zijlstra
2019-03-19 20:48   ` Stephane Eranian
2019-03-19 21:00     ` Peter Zijlstra
2019-03-20 13:14       ` Peter Zijlstra
2019-03-20 12:23     ` Peter Zijlstra
2019-03-14 13:01 ` [RFC][PATCH 5/8] perf/x86/intel: Optimize intel_get_excl_constraints() Peter Zijlstra
2019-03-19 23:43   ` Stephane Eranian
2019-03-14 13:01 ` [RFC][PATCH 6/8] perf/x86: Clear ->event_constraint[] on put Peter Zijlstra
2019-03-19 21:50   ` Stephane Eranian
2019-03-20 12:25     ` Peter Zijlstra [this message]
2019-03-14 13:01 ` [RFC][PATCH 7/8] perf/x86: Optimize x86_schedule_events() Peter Zijlstra
2019-03-19 23:55   ` Stephane Eranian
2019-03-20 13:11     ` Peter Zijlstra
2019-03-20 19:30       ` Stephane Eranian
2019-03-14 13:01 ` [RFC][PATCH 8/8] perf/x86: Add sanity checks to x86_schedule_events() Peter Zijlstra
2019-03-15  7:15 ` [RFC][PATCH 0/8] perf/x86: event scheduling cleanups Stephane Eranian
2019-03-15  7:15   ` Stephane Eranian
2019-03-15  8:01     ` Peter Zijlstra

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