Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756196AbbKRPvy (ORCPT ); Wed, 18 Nov 2015 10:51:54 -0500 Received: from mga11.intel.com ([192.55.52.93]:12692 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756117AbbKRPvw (ORCPT ); Wed, 18 Nov 2015 10:51:52 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,313,1444719600"; d="scan'208";a="853755485" Subject: Re: [PATCH 3/4] sched: introduce synchronized idle injection To: Morten Rasmussen , Jacob Pan References: <1447444387-23525-1-git-send-email-jacob.jun.pan@linux.intel.com> <1447444387-23525-4-git-send-email-jacob.jun.pan@linux.intel.com> <20151118154457.GD30184@e105550-lin.cambridge.arm.com> Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , John Stultz , LKML , Srinivas Pandruvada , Len Brown , Rafael Wysocki , Eduardo Valentin , Paul Turner From: Arjan van de Ven Message-ID: <564C9E93.8030901@linux.intel.com> Date: Wed, 18 Nov 2015 07:51:47 -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: <20151118154457.GD30184@e105550-lin.cambridge.arm.com> 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: 1149 Lines: 23 On 11/18/2015 7:44 AM, Morten Rasmussen wrote: > I would not necessarily want to punish all cpus > system-wide if we have local overheating in one corner. If would rather > have it apply to only the overheating socket in a multi-socket machine > and only the big cores in a big.LITTLE system. most of the time thermal issues aren't inside the SOC, but on a system level due to cheap heat spreaders or outright lack of space due to thinness. But even if you have one part of the die too hot: For core level idle injection, no need to synchronize that; the reason to synchronize is generally that when ALL cores are idle, additional power savings kick in (like memory going to self refresh, fabrics power gating etc); those additional power savings are what makes this more efficient than just voltage/frequency scaling at the bottom of that range... not so much the fact that things are just idle. -- 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/