Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161420AbbKEOXA (ORCPT ); Thu, 5 Nov 2015 09:23:00 -0500 Received: from mga11.intel.com ([192.55.52.93]:44419 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965450AbbKEOW7 (ORCPT ); Thu, 5 Nov 2015 09:22:59 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,247,1444719600"; d="scan'208";a="843299113" Subject: Re: [RFC PATCH 3/3] sched: introduce synchronized idle injection To: Peter Zijlstra , Jacob Pan References: <1446509428-5616-1-git-send-email-jacob.jun.pan@linux.intel.com> <1446509428-5616-4-git-send-email-jacob.jun.pan@linux.intel.com> <20151103133120.GD17308@twins.programming.kicks-ass.net> <20151103084501.289ec5d1@yairi> <20151105100922.GA3604@twins.programming.kicks-ass.net> Cc: Thomas Gleixner , LKML , Paul Turner , Len Brown , Srinivas Pandruvada , Tim Chen , Andi Kleen , Rafael Wysocki From: Arjan van de Ven Message-ID: <563B6642.2090803@linux.intel.com> Date: Thu, 5 Nov 2015 06:22:58 -0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151105100922.GA3604@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 911 Lines: 25 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. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/