From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751716AbeFEIpk (ORCPT ); Tue, 5 Jun 2018 04:45:40 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:36672 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751495AbeFEIpi (ORCPT ); Tue, 5 Jun 2018 04:45:38 -0400 Date: Tue, 5 Jun 2018 14:15:30 +0530 From: Gautham R Shenoy To: Michael Ellerman Cc: "Gautham R. Shenoy" , "Rafael J. Wysocki" , Daniel Lezcano , Stewart Smith , Michael Neuling , Vaidyanathan Srinivasan , Shilpasri G Bhat , Akshay Adiga , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH] cpuidle:powernv: Make the snooze timeout dynamic. Reply-To: ego@linux.vnet.ibm.com References: <1527768909-32637-1-git-send-email-ego@linux.vnet.ibm.com> <87fu22bxlf.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87fu22bxlf.fsf@concordia.ellerman.id.au> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 x-cbid: 18060508-0020-0000-0000-00000E198E2C X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009133; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000265; SDB=6.01042577; UDB=6.00533873; IPR=6.00821707; MB=3.00021472; MTD=3.00000008; XFM=3.00000015; UTC=2018-06-05 08:45:36 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18060508-0021-0000-0000-000061C3491D Message-Id: <20180605084529.GA5656@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-05_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=970 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806050106 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Michael, On Mon, Jun 04, 2018 at 09:27:40PM +1000, Michael Ellerman wrote: > "Gautham R. Shenoy" writes: > > > From: "Gautham R. Shenoy" > > > > The commit 78eaa10f027c ("cpuidle: powernv/pseries: Auto-promotion of > > snooze to deeper idle state") introduced a timeout for the snooze idle > > state so that it could be eventually be promoted to a deeper idle > > state. The snooze timeout value is static and set to the target > > residency of the next idle state, which would train the cpuidle > > governor to pick the next idle state eventually. > > > > The unfortunate side-effect of this is that if the next idle state(s) > > is disabled, the CPU will forever remain in snooze, despite the fact > > that the system is completely idle, and other deeper idle states are > > available. > > That sounds like a bug, I'll add? > Yes, this is a bug-fix for a customer scenario which we encountered recently. > Fixes: 78eaa10f027c ("cpuidle: powernv/pseries: Auto-promotion of snooze to deeper idle state") > Cc: stable@vger.kernel.org # v4.2+ This patch applies cleanly from v4.13 onwards. Prior to that there are some (minor) conflicts. Should I spin a version separately for the prior stable versions ? > > cheers >