From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755691AbcFQPck (ORCPT ); Fri, 17 Jun 2016 11:32:40 -0400 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:9734 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932125AbcFQPch convert rfc822-to-8bit (ORCPT ); Fri, 17 Jun 2016 11:32:37 -0400 From: Jisheng Zhang To: Peter Zijlstra , "Paul E. McKenney" CC: "Rafael J. Wysocki" , "Rafael J. Wysocki" , Viresh Kumar , "linux-pm@vger.kernel.org" , "Linux Kernel Mailing List" Subject: RE: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early") Thread-Topic: regression caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early") Thread-Index: AQHRyK1jr0enS8HWkEWC6eDb0vCMaQ== Date: Fri, 17 Jun 2016 15:32:00 +0000 Message-ID: <2c6f6aab934141e08d9636739a9f7a94@SC-EXCH02.marvell.com> References: <20160617163023.5bb374f8@xhacker> <20160617164054.6339c5d4@xhacker> <20160617131651.GU3923@linux.vnet.ibm.com>,<20160617140353.GQ30154@twins.programming.kicks-ass.net> In-Reply-To: <20160617140353.GQ30154@twins.programming.kicks-ass.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.36.250.51] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-06-17_09:,, signatures=0 X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1606170178 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, First of all, sorry for top post, only webmail is available now. Second, sorry again for report incorrect commit, I were too tired this morning so I remember the wrong commit. The regression is caused by bb6ab52f2bef ("intel_pstate: Do not set utilization update hook too early"), so I update the email title. here is the bisect log: # good: [9735a22799b9214d17d3c231fe377fc852f042e9] Linux 4.6-rc2 git bisect good 9735a22799b9214d17d3c231fe377fc852f042e9 # bad: [bf16200689118d19de1b8d2a3c314fc21f5dc7bb] Linux 4.6-rc3 git bisect bad bf16200689118d19de1b8d2a3c314fc21f5dc7bb # good: [839a3f765728cdca0057a12e2dc0bf669ac1c22e] Merge branch 'for-linus-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs git bisect good 839a3f765728cdca0057a12e2dc0bf669ac1c22e # bad: [63b106a87dd84283e21aa2ce476732633eaab11d] Merge tag 'md/4.6-rc2-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md git bisect bad 63b106a87dd84283e21aa2ce476732633eaab11d # good: [30d237a6c2e9be1bb816fe8e787b88fd7aad833b] Merge tag 'mac80211-for-davem-2016-04-06' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211 git bisect good 30d237a6c2e9be1bb816fe8e787b88fd7aad833b # bad: [fa81e66ec8648f62e96e95e53db2ea95a4b57b26] Merge branches 'pm-cpufreq', 'pm-cpuidle' and 'acpi-cppc' git bisect bad fa81e66ec8648f62e96e95e53db2ea95a4b57b26 # good: [08820546e4c30c84d0a1f1a49df055e1719c07ea] intel_idle: Propagate hot plug errors. git bisect good 08820546e4c30c84d0a1f1a49df055e1719c07ea # bad: [b318556479cc923970a79d6c2311138581c0db83] cpufreq: dt: Drop stale comment git bisect bad b318556479cc923970a79d6c2311138581c0db83 # bad: [febce40febcff3ccdb33f63456ffc4cfc61640c8] intel_pstate: Avoid extra invocation of intel_pstate_sample() git bisect bad febce40febcff3ccdb33f63456ffc4cfc61640c8 # bad: [bb6ab52f2befe1fb29ac198f27d8a6aadf510f81] intel_pstate: Do not set utilization update hook too early git bisect bad bb6ab52f2befe1fb29ac198f27d8a6aadf510f81 # first bad commit: [bb6ab52f2befe1fb29ac198f27d8a6aadf510f81] intel_pstate: Do not set utilization update hook too early ________________________________________ From: Peter Zijlstra [peterz@infradead.org] Sent: Friday, June 17, 2016 22:03 To: Paul E. McKenney Cc: Rafael J. Wysocki; Jisheng Zhang; Rafael J. Wysocki; Viresh Kumar; linux-pm@vger.kernel.org; Linux Kernel Mailing List Subject: Re: regression caused by 08f511fd41c3 ("cpufreq: Reduce cpufreq_update_util() overhead a bit") On Fri, Jun 17, 2016 at 06:16:51AM -0700, Paul E. McKenney wrote: > > Paul, Peter, any ideas about what may be going on here? > > Looks to me like this commit moved some code from synchronize_rcu() to > synchronize_sched(). Assuming that this is a CONFIG_PREEMPT=y system, > might there have been a decrease in the wakeups from the rcu_preempt > kthread? The 'funny' thing is though; those synchronize thingies are only reached when we change cpufreq policy, so things like: for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i ; done Something which is hardly possible when idle. Weird.