From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dietmar Eggemann Subject: Re: [RFC PATCH 2/3] sched/cpuset: Keep track of SCHED_DEADLINE tasks in cpusets Date: Wed, 22 Mar 2023 14:18:47 +0100 Message-ID: References: <20230315121812.206079-1-juri.lelli@redhat.com> <20230315121812.206079-3-juri.lelli@redhat.com> <7a3b31bf-4f6a-6525-9c6a-2bae44d7b0af@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Content-Language: en-US In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" To: Juri Lelli , Waiman Long Cc: Peter Zijlstra , Ingo Molnar , Qais Yousef , Tejun Heo , Zefan Li , Johannes Weiner , Hao Luo , 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 15/03/2023 18:14, Juri Lelli wrote: > On 15/03/23 11:46, Waiman Long wrote: >> >> On 3/15/23 08:18, Juri Lelli wrote: [...] >>> @@ -2472,6 +2492,11 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) >>> ret = security_task_setscheduler(task); >>> if (ret) >>> goto out_unlock; >>> + >>> + if (dl_task(task)) { >>> + cs->nr_deadline_tasks++; >>> + cpuset_attach_old_cs->nr_deadline_tasks--; >>> + } >>> } >> >> Any one of the tasks in the cpuset can cause the test to fail and abort the >> attachment. I would suggest that you keep a deadline task transfer count in >> the loop and then update cs and cpouset_attach_old_cs only after all the >> tasks have been iterated successfully. > > Right, Dietmar I think commented pointing out something along these > lines. Think though we already have this problem with current > task_can_attach -> dl_cpu_busy which reserves bandwidth for each tasks > in the destination cs. Will need to look into that. Do you know which > sort of operation would move multiple tasks at once? Moving the process instead of the individual tasks makes cpuset_can_attach() have to deal with multiple tasks. # ps2 | grep DLN 1614 1615 140 0 - DLN thread0-0 1614 1616 140 0 - DLN thread0-1 1614 1617 140 0 - DLN thread0-2 # echo 1614 > /sys/fs/cgroup/cpuset/cs2/cgroup.procs