From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH] ARM: cpuidle: Support asymmetric idle definition Date: Mon, 22 May 2017 14:59:14 +0100 Message-ID: <4299ef3e-1cb2-983c-f0c1-13f16724256d@arm.com> References: <1495212343-24873-1-git-send-email-daniel.lezcano@linaro.org> <850fab54-d6e6-7b4c-631a-f4ee658c96fa@arm.com> <45754d0a-6a98-2987-74ed-429926d89cbc@arm.com> <3ce7048e-6d9d-9e46-a6fb-4d3263231536@arm.com> <20170522133452.GC9325@leoy-ThinkPad-T440> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from foss.arm.com ([217.140.101.70]:37780 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933851AbdEVN7R (ORCPT ); Mon, 22 May 2017 09:59:17 -0400 In-Reply-To: <20170522133452.GC9325@leoy-ThinkPad-T440> Content-Language: en-US Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Leo Yan Cc: Sudeep Holla , Daniel Lezcano , rjw@rjwysocki.net, lorenzo.pieralisi@arm.com, "open list:CPUIDLE DRIVERS" , open list On 22/05/17 14:34, Leo Yan wrote: > Hi Sudeep, > > On Mon, May 22, 2017 at 02:02:12PM +0100, Sudeep Holla wrote: > > [...] > >>>>>> On 19/05/17 17:45, Daniel Lezcano wrote: >>>>>>> Some hardware have clusters with different idle states. The current code does >>>>>>> not support this and fails as it expects all the idle states to be identical. >>>>>>> >>>>>>> Because of this, the Mediatek mtk8173 had to create the same idle state for a >>>>>>> big.Little system and now the Hisilicon 960 is facing the same situation. >>>>>>> >>>>>> >>>>>> While I agree the we don't support them today, it's better to benchmark >>>>>> and record/compare the gain we get with the support for cluster based >>>>>> idle states. >>>>> >>>>> Sorry, I don't get what you are talking about. What do you want to >>>>> benchmark ? Cluster idling ? >>>>> >>>> >>>> OK, I was not so clear. I had a brief chat with Lorenzo, we have few >>>> reason to have this support: >>>> 1. Different number of states between clusters >>>> 2. Different latencies(this is the one I was referring above, generally >>>> we keep worst case timings here and wanted to see if any platform >>>> measured improvements with different latencies in the idle states) >>> >>> I don't see the point. Are you putting into question the big little design? >>> >> >> Not exactly. Since they are generally worst case number, I wanted to >> check if someone saw real benefit with 2 different set of values. >> Anyways that's not important or blocking, just raised a point, so that >> we can stick some benchmarking results with this. > > In case you are interesting for Hikey960 idle states, you could see > the two clustsers have different idle states: > http://termbin.com/d7ed Probably this if off-topic, but I found CPU_NAP_0 really interesting: 1. CPU_NAP_0 has arm,psci-suspend-param as 0x00000000 which generally not recommended to avoid conflict with WFI 2. Initially I assumed, CPU_NAP_0 is retention/standby state, but then I see "local-timer-stop", which indicates it's power down state which means arm,psci-suspend-param is wrong. -- Regards, Sudeep