From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH 0/6] sched/deadline: cpuset: Rework DEADLINE bandwidth restoration Date: Wed, 29 Mar 2023 10:34:57 -0400 Message-ID: References: <20230329125558.255239-1-juri.lelli@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680100504; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=j6Qltz9GS2xYDRDWB9RaugYoeUKsxXmeQuDRMPnbUIY=; b=emkoH0Yd493ttonN89IldVIZGsmkpEJK/e+45YtmBXKMCmSbedWINogqsthzUUbicsZNzt 3FVHmZh56EehreA7HpWfUFbJqorkMVQPB6k3loAHxYVT0Dv45WATX2Zza/3ojJV6wh2dZZ J5UO/9hNSIZ6oTSCz7Exk8br5m1jcXU= Content-Language: en-US In-Reply-To: <20230329125558.255239-1-juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Juri Lelli , Peter Zijlstra , Ingo Molnar , Qais Yousef , Tejun Heo , Zefan Li , Johannes Weiner , Hao Luo Cc: 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 , Sudeep Holla On 3/29/23 08:55, 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 > > Best, > Juri > > 1 - https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef-wp2msK0BRk8tq7phqP6ubQ@public.gmane.org/ > 2 - https://lore.kernel.org/lkml/20230315121812.206079-1-juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org/ > > Dietmar Eggemann (2): > sched/deadline: Create DL BW alloc, free & check overflow interface > cgroup/cpuset: Free DL BW in case can_attach() fails > > Juri Lelli (4): > cgroup/cpuset: Rename functions dealing with DEADLINE accounting > sched/cpuset: Bring back cpuset_mutex > sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets > cgroup/cpuset: Iterate only if DEADLINE tasks are present > > include/linux/cpuset.h | 12 ++- > include/linux/sched.h | 4 +- > kernel/cgroup/cgroup.c | 4 + > kernel/cgroup/cpuset.c | 232 ++++++++++++++++++++++++++-------------- > kernel/sched/core.c | 41 ++++--- > kernel/sched/deadline.c | 67 +++++++++--- > kernel/sched/sched.h | 2 +- > 7 files changed, 240 insertions(+), 122 deletions(-) Other than some minor issues that I have talked in earlier emails, the patch series looks good to me. You can add my ack once the issues are fixed. Acked-by: Waiman Long