From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juri Lelli Subject: Re: [PATCH 0/6] sched/deadline: cpuset: Rework DEADLINE bandwidth restoration Date: Thu, 20 Apr 2023 16:15:33 +0200 Message-ID: References: <20230329125558.255239-1-juri.lelli@redhat.com> <20230418141127.zbvsf7lwk27zvipt@airbuntu> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682000139; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=AM2iS5p+M5vdfcO5gATf9U1kgTLr8hfoHFhkOm5c9I4=; b=YWRtaXy/S+NnBFUZ3aDITa4WIf8ttwZWTKMsJjgj4Jk9t8Z8YmaR+UdOTO1ErbyeQM1kCt nudSlN5y2Qpiv8jzlaCLZ9CKAwiqbGtzw9X8lB/XP60kOIz82bvCx8HURqDOcZxjNFLhZT rF9cAF2KEMXL13P8OKy9o4W2rfwpo44= Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long Cc: Qais Yousef , Peter Zijlstra , Ingo Molnar , Tejun Heo , Zefan Li , Johannes Weiner , Hao Luo , Dietmar Eggemann , Steven Rostedt , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, luca.abeni-5rdYK369eBLQB0XuIGIEkQ@public.gmane.org, claudio-YOzL5CV4y4YG1A2ADO40+w@public.gmane.org, tommaso.cucinotta-5rdYK369eBLQB0XuIGIEkQ@public.gmane.org, bristot-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mathieu.poirier-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vincent Guittot , Wei Wang , Rick Yiu , Quentin Perret , Heiko Carstens , Vasily Gorbik , Alexander Gordeev On 18/04/23 10:31, Waiman Long wrote: > On 4/18/23 10:11, Qais Yousef wrote: > > On 03/29/23 14:55, Juri Lelli wrote: > > > Qais reported [1] that iterating over all tasks when rebuilding root > > > domains for finding out which ones are DEADLINE and need their bandwidth > > > correctly restored on such root domains can be a costly operation (10+ > > > ms delays on suspend-resume). He proposed we skip rebuilding root > > > domains for certain operations, but that approach seemed arch specific > > > and possibly prone to errors, as paths that ultimately trigger a rebuild > > > might be quite convoluted (thanks Qais for spending time on this!). > > > > > > To fix the problem > > > > > > 01/06 - Rename functions deadline with DEADLINE accounting (cleanup > > > suggested by Qais) - no functional change > > > 02/06 - Bring back cpuset_mutex (so that we have write access to cpusets > > > from scheduler operations - and we also fix some problems > > > associated to percpu_cpuset_rwsem) > > > 03/06 - Keep track of the number of DEADLINE tasks belonging to each cpuset > > > 04/06 - Create DL BW alloc, free & check overflow interface for bulk > > > bandwidth allocation/removal - no functional change > > > 05/06 - Fix bandwidth allocation handling for cgroup operation > > > involving multiple tasks > > > 06/06 - Use this information to only perform the costly iteration if > > > DEADLINE tasks are actually present in the cpuset for which a > > > corresponding root domain is being rebuilt > > > > > > With respect to the RFC posting [2] > > > > > > 1 - rename DEADLINE bandwidth accounting functions - Qais > > > 2 - call inc/dec_dl_tasks_cs from switched_{to,from}_dl - Qais > > > 3 - fix DEADLINE bandwidth allocation with multiple tasks - Waiman, > > > contributed by Dietmar > > > > > > This set is also available from > > > > > > https://github.com/jlelli/linux.git deadline/rework-cpusets > > Is this just waiting to be picked up or still there's something to be addressed > > still? > > There are some changes to cpuset code recently and so I believe that this > patch series may need to be refreshed to reconcile the changes. Yeah, will soon take a look. Thanks! Juri