From: Mel Gorman <mgorman@techsingularity.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Mike Galbraith <efault@gmx.de>,
Matt Fleming <matt@codeblueprint.co.uk>,
LKML <linux-kernel@vger.kernel.org>,
srinivas.pandruvada@linux.intel.com
Subject: Re: [PATCH 4/4] sched/fair: Use a recently used CPU as an idle candidate and the basis for SIS
Date: Wed, 31 Jan 2018 11:54:06 +0000 [thread overview]
Message-ID: <20180131115406.4g7oj46xhmteefc5@techsingularity.net> (raw)
In-Reply-To: <20180131101710.GM2269@hirez.programming.kicks-ass.net>
On Wed, Jan 31, 2018 at 11:17:10AM +0100, Peter Zijlstra wrote:
> On Wed, Jan 31, 2018 at 10:22:49AM +0100, Rafael J. Wysocki wrote:
> > On Tuesday, January 30, 2018 2:15:31 PM CET Peter Zijlstra wrote:
>
> > > IA32_HWP_REQUEST has "Minimum_Performance", "Maximum_Performance" and
> > > "Desired_Performance" fields which can be used to give explicit
> > > frequency hints. And we really _should_ be doing that.
> > >
> > > Because, esp. in this scenario; a task migrating; the hardware really
> > > can't do anything sensible, whereas the OS _knows_.
> >
> > But IA32_HWP_REQUEST is not a cheap MSR to write to.
>
> That just means we might need to throttle writing to it, like it already
> does for the regular pstate (PERF_CTRL) msr in any case (also, is that a
> cheap msr?)
>
> Not touching it at all seems silly.
>
Note that even if we do such programming, it would still be desirable to
minimise the number of times we have to reprogram it so the series as it
stands would still be useful.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2018-01-31 11:54 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 10:45 [PATCH 0/4] Reduce migrations and unnecessary spreading of load to multiple CPUs Mel Gorman
2018-01-30 10:45 ` [PATCH 1/4] sched/fair: Remove unnecessary parameters from wake_affine_idle Mel Gorman
2018-02-06 11:55 ` [tip:sched/urgent] sched/fair: Remove unnecessary parameters from wake_affine_idle() tip-bot for Mel Gorman
2018-01-30 10:45 ` [PATCH 2/4] sched/fair: Restructure wake_affine to return a CPU id Mel Gorman
2018-02-06 11:56 ` [tip:sched/urgent] sched/fair: Restructure wake_affine*() " tip-bot for Mel Gorman
2018-01-30 10:45 ` [PATCH 3/4] sched/fair: Do not migrate if the prev_cpu is idle Mel Gorman
2018-02-06 11:56 ` [tip:sched/urgent] " tip-bot for Mel Gorman
2018-01-30 10:45 ` [PATCH 4/4] sched/fair: Use a recently used CPU as an idle candidate and the basis for SIS Mel Gorman
2018-01-30 11:50 ` Peter Zijlstra
2018-01-30 12:57 ` Mel Gorman
2018-01-30 13:15 ` Peter Zijlstra
2018-01-30 13:25 ` Mel Gorman
2018-01-30 13:40 ` Peter Zijlstra
2018-01-30 14:06 ` Mel Gorman
2018-01-31 9:22 ` Rafael J. Wysocki
2018-01-31 10:17 ` Peter Zijlstra
2018-01-31 11:54 ` Mel Gorman [this message]
2018-01-31 17:44 ` Srinivas Pandruvada
2018-02-01 9:11 ` Peter Zijlstra
2018-02-01 7:50 ` Rafael J. Wysocki
2018-02-01 9:11 ` Peter Zijlstra
2018-02-01 13:18 ` Srinivas Pandruvada
2018-02-02 11:00 ` Rafael J. Wysocki
2018-02-02 14:54 ` Srinivas Pandruvada
2018-02-02 19:48 ` Mel Gorman
2018-02-02 20:01 ` Srinivas Pandruvada
2018-02-05 11:10 ` Mel Gorman
2018-02-05 17:04 ` Srinivas Pandruvada
2018-02-05 17:50 ` Mel Gorman
2018-02-04 8:42 ` Rafael J. Wysocki
2018-02-04 8:38 ` Rafael J. Wysocki
2018-02-02 11:42 ` Rafael J. Wysocki
2018-02-02 12:46 ` Peter Zijlstra
2018-02-02 12:55 ` Peter Zijlstra
2018-02-02 14:08 ` Peter Zijlstra
2018-02-03 16:30 ` Srinivas Pandruvada
2018-02-05 10:44 ` Peter Zijlstra
2018-02-05 10:58 ` Ingo Molnar
2018-02-02 12:58 ` Peter Zijlstra
2018-02-02 13:27 ` Mel Gorman
2018-01-30 13:15 ` Mike Galbraith
2018-01-30 13:25 ` Peter Zijlstra
2018-01-30 13:35 ` Mike Galbraith
2018-01-30 11:53 ` Peter Zijlstra
2018-01-30 12:59 ` Mel Gorman
2018-01-30 13:06 ` Peter Zijlstra
2018-01-30 13:18 ` Mel Gorman
2018-02-06 11:56 ` [tip:sched/urgent] " tip-bot for Mel Gorman
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