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From: Arjan van de Ven <arjan@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>, Paul Turner <pjt@google.com>,
	Len Brown <len.brown@intel.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Andi Kleen <andi.kleen@intel.com>,
	Rafael Wysocki <rafael.j.wysocki@intel.com>
Subject: Re: [RFC PATCH 3/3] sched: introduce synchronized idle injection
Date: Thu, 5 Nov 2015 06:22:58 -0800	[thread overview]
Message-ID: <563B6642.2090803@linux.intel.com> (raw)
In-Reply-To: <20151105100922.GA3604@twins.programming.kicks-ass.net>

On 11/5/2015 2:09 AM, Peter Zijlstra wrote:

> I can see such a scheme having a fairly big impact on latency, esp. with
> forced idleness such as this. That's not going to be popular for many
> workloads.

idle injection is a last ditch effort in thermal management, before
this gets used the hardware already has clamped you to a low frequency,
reduced memory speeds, probably dimmed your screen etc etc.

at this point there are 3 choices
1) Shut off the device
2) do uncoordinated idle injection for 40% of the time
3) do coordinated idle injection for 5% of the time

as much as force injecting idle in a synchronized way sucks, the alternatives are worse.


>


  reply	other threads:[~2015-11-05 14:23 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-03  0:10 [RFC PATCH 0/3] CFS idle injection Jacob Pan
2015-11-03  0:10 ` [RFC PATCH 1/3] ktime: add a roundup function Jacob Pan
2015-11-03  0:10 ` [RFC PATCH 2/3] timer: relax tick stop in idle entry Jacob Pan
2015-11-03  0:10 ` [RFC PATCH 3/3] sched: introduce synchronized idle injection Jacob Pan
2015-11-03 13:31   ` Peter Zijlstra
2015-11-03 14:16     ` Jacob Pan
2015-11-03 16:45     ` Jacob Pan
2015-11-05 10:09       ` Peter Zijlstra
2015-11-05 14:22         ` Arjan van de Ven [this message]
2015-11-05 14:33           ` Peter Zijlstra
2015-11-05 14:48             ` Peter Zijlstra
2015-11-05 15:28             ` Arjan van de Ven
2015-11-05 16:52               ` Peter Zijlstra
2015-11-05 18:55                 ` Thomas Gleixner
2015-11-05 18:47               ` Thomas Gleixner
2015-11-05 15:32             ` Jacob Pan
2015-11-05 16:06               ` Arjan van de Ven
2015-11-05 19:27         ` Jacob Pan
2015-11-05 19:32           ` Jacob Pan
2015-11-05 13:59     ` Peter Zijlstra
2015-11-05 23:36       ` Jacob Pan
2015-11-06  7:45         ` Peter Zijlstra
2015-11-06 23:49           ` Jacob Pan
2015-11-10  0:19             ` Jacob Pan
2015-11-04  6:06 ` [RFC PATCH 0/3] CFS " Eduardo Valentin
2015-11-04 16:58   ` Jacob Pan
2015-11-04 17:05     ` Srinivas Pandruvada
2015-11-04 18:43       ` Eduardo Valentin
2015-11-05 10:12     ` Peter Zijlstra
2015-11-06 16:50       ` Punit Agrawal
2015-11-06 19:18         ` Jacob Pan
2015-11-09 11:56           ` Punit Agrawal
2015-11-09 14:15             ` Peter Zijlstra
2015-11-09 14:43               ` Jacob Pan
2015-11-10 10:07               ` Juri Lelli
2015-11-10 10:34                 ` Peter Zijlstra
2015-11-10 10:56                   ` Juri Lelli
2015-11-09 14:36             ` Jacob Pan
2015-11-06 18:30       ` Dietmar Eggemann
2015-11-06 19:10         ` Jacob Pan
2015-11-06 21:55           ` Dietmar Eggemann
2015-11-09 21:23             ` Jacob Pan
2015-11-09 21:45               ` Peter Zijlstra

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