From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761351Ab3DBJhO (ORCPT ); Tue, 2 Apr 2013 05:37:14 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:18330 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760147Ab3DBJhL (ORCPT ); Tue, 2 Apr 2013 05:37:11 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 X-AuditID: cbfee691-b7f5f6d000002fda-b2-515aa6c4ccd3 Content-transfer-encoding: 8BIT Message-id: <515AA6C3.3060408@samsung.com> Date: Tue, 02 Apr 2013 18:37:07 +0900 From: jonghwa3.lee@samsung.com User-Agent: Mozilla/5.0 (X11; Linux i686; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 To: Daniel Lezcano Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, MyungJoo Ham , Lukasz Majewski , Kyungmin Park , Chanwoo Choi , sw0312.kim@samsung.com, m.szyprowski@samsung.com Subject: Re: [RFC PATCH 1/2] cpuidle: Add idle enter/exit time stamp for notifying current idle state. References: <1364804657-16590-1-git-send-email-jonghwa3.lee@samsung.com> <1364804657-16590-2-git-send-email-jonghwa3.lee@samsung.com> <515A65DB.8070803@linaro.org> <515A77FC.70008@samsung.com> <515A8A21.6070509@linaro.org> In-reply-to: <515A8A21.6070509@linaro.org> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrNIsWRmVeSWpSXmKPExsVy+t8zXd0jy6ICDSa2qFo8bfrBbnH9y3NW i3mfZS3ONr1ht3jzcDOjxeVdc9gsPvceYbRYe+Quu8XtxhVsFv0Le5ksZkx+yebA7XHn2h42 j74tqxg9Hi1uYfT4vEkugCWKyyYlNSezLLVI3y6BK2PhsfvMBfdFK1YseMTWwLhYsIuRk0NC wETiwbm1zBC2mMSFe+vZuhi5OIQEljFKrD10l6mLkQOsaOphKYj4dKD43GVMIA28AoISPybf YwGpYRaQlzhyKRskzCygLjFp3iJmiPqXjBKfr15mh6jXkpjyB6Sek4NFQFVi69EvYIvZBOQk 3jZ9YwSZIyoQIfGrnwMkLCKgJ9H4vo0JZA6zwA0miWVXmsF6hQUyJOY+usUCseAJo8THhr9g CU6gBRcaT4MlJAQ+sktcOPqAEWKbgMS3yYdYIL6Rldh0AOpjSYmDK26wTGAUm4Xkn1kI/8xC 8s8CRuZVjKKpBckFxUnpRaZ6xYm5xaV56XrJ+bmbGCEROXEH4/0D1ocYk4E2TmSWEk3OB0Z0 Xkm8obGZkYWpiamxkbmlGWnCSuK86i3WgUIC6YklqdmpqQWpRfFFpTmpxYcYmTg4pRoYj/pE y2Q1n/N80SKUc/yGl/PD+LkdOn8S7k+P+NVjnCQrUsZfNcNihk+CDsOpA5//efzQ1/5s7tw5 5fEpvcbqRXrd6hGnIixXr9Sf03PPbYlGoqORxiX5BHNTh6p/gWcdO+pP5l1qKFBmK6quC04w vDhhyvcjZhmH/nH4y55kl7j6UHGBZrwSS3FGoqEWc1FxIgD5JlmB3gIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrBKsWRmVeSWpSXmKPExsVy+t9jQd0jy6ICDRY9krN42vSD3eL6l+es FvM+y1qcbXrDbvHm4WZGi8u75rBZfO49wmix9shddovbjSvYLPoX9jJZzJj8ks2B2+POtT1s Hn1bVjF6PFrcwujxeZNcAEtUA6NNRmpiSmqRQmpecn5KZl66rZJ3cLxzvKmZgaGuoaWFuZJC XmJuqq2Si0+ArltmDtBVSgpliTmlQKGAxOJiJX07TBNCQ9x0LWAaI3R9Q4LgeowM0EDCOsaM hcfuMxfcF61YseARWwPjYsEuRg4OCQETiamHpboYOYFMMYkL99azdTFycQgJTGeUWDt3GRNI gldAUOLH5HssIPXMAvISRy5lg4SZBdQlJs1bxAxR/5JR4vPVy+wQ9VoSU/6A1HNysAioSmw9 +oUZxGYTkJN42/SNEWSOqECExK9+DpCwiICeROP7NiaQOcwCN5gkll1pBusVFsiQmPvoFgvE gieMEh8b/oIlOIEWXGg8zTKBUWAWkvtmIdw3C8l9CxiZVzGKphYkFxQnpeca6hUn5haX5qXr JefnbmIEx/szqR2MKxssDjEKcDAq8fA6zIkMFGJNLCuuzD3EKMHBrCTCu1U3KlCINyWxsiq1 KD++qDQntfgQYzLQdxOZpUST84GpKK8k3tDYxMzI0sjM2MTc2Jg0YSVx3gOt1oFCAumJJanZ qakFqUUwW5g4OKUaGLN9fmj9en30tbxQYdGH7AKDxUfO2kUvnMQ2geHahuZW2T1mm831Gs+n yDt4lstNsq1+UFUko1MmcL43QdVuzsaIKNOr5va7q8rZVwt93TrVIFXmQdr/P7zPyqcG/5q0 VO8kh9rVp/zVrzpnME84d/P6iX27VltcuRKwqaHao758/dFLdyXOrFJiKc5INNRiLipOBAAl dC4fOwMAAA== DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013년 04월 02일 16:34, Daniel Lezcano wrote: > On 04/02/2013 08:17 AM, jonghwa3.lee@samsung.com wrote: >> On 2013년 04월 02일 14:00, Daniel Lezcano wrote: >> >>> On 04/01/2013 10:24 AM, Jonghwa Lee wrote: >>>> This patch adds idle state time stamp to cpuidle device structure to >>>> notify its current idle state. If last enter time is newer than last >>>> exit time, then it means that the core is in idle now. >>>> >>>> Signed-off-by: Jonghwa Lee >>>> --- >>> >>> The patch description does not explain what problem you want to solve, >>> how to solve it and the patch itself shows nothing. >>> >>> Could you elaborate ? >> >> >> I'm sorry for lacking description. I supplement more. >> >> This patch does add time-stamp for idle enter/exit only nothing more. >> The reason why I needed them is that I wanted to know current cpu idle >> state. It is hard to know whether cpu is in idle or not now. > > Did you looked at: > > include/linux/sched.h:extern int idle_cpu(int cpu); > Yes, I did. > ? > >> When I check the cpuidle state usage, sometimes the information is wrong. >> Because it is updated only when the cpu exits the idle state. So while the >> cpu is idling, the cpuidle state usage holds past one. Therefore I put >> the time-stamp for cpuidle enter/exit for checking current idling and >> calculating idle state usage correctly. >> >> I just make this patch temporary for my cpufreq governor work. So, it just >> use time-stamp for all idle state together. After RFC working, I have a plan >> to update this patch to use timestamp for each idle state. > > I suggest you look at the enter_idle / exit_idle function and make your > governor to subscribe to the IDLE_START/EXIT notifiers. > > arch/x86/kernel/process.c > > These are defined for the x86 architecture, maybe worth to add it to > another architecture. > Thanks for your opinion. Actually, I work on ARM architecture and I knew that the attempt of applying idle notifier was failed. You probably knew it, because the link you gave me before is that attempt. (https://lkml.org/lkml/2012/2/7/504) :) Currently, there is only notifying call which is for led in arch/arm/kernel/process.c and I think it isn't for me to use. Anyway, Do you really think it is better way to use notifier than my way? Because I think it is too heavy for me. On my board, sometimes entering idle happened hundreds times during the 100ms. I don't want to call notifier that much time. IMO, just moving local variable to per-cpu variable for showing the enter/exit time looks better although it requires code modification on cpudile side. What do you think? Thanks, Jonghwa. > Thanks > -- Daniel >