From: Peter Zijlstra <peterz@infradead.org> To: Zefan Li <lizefan@huawei.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com>, Ingo Molnar <mingo@kernel.org>, Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Cgroups <cgroups@vger.kernel.org> Subject: Re: [PATCH] sched: Relax a restriction in sched_rt_can_attach() Date: Mon, 4 May 2015 14:37:38 +0200 [thread overview] Message-ID: <20150504123738.GZ21418@twins.programming.kicks-ass.net> (raw) In-Reply-To: <554737AE.5040402@huawei.com> On Mon, May 04, 2015 at 05:11:10PM +0800, Zefan Li wrote: > Some degree of flexibility is provided so that you may disable some controllers > in a subtree. For example: > > root ---> child1 > (cpuset,memory,cpu) (cpuset,memory) > \ > \-> child2 > (cpu) Uhm, how does that work? Would a task their effective cgroup be the first parent that has a controller enabled? In particular, in your example, if T were part of child1, would its cpu controller be root? > I just realized we allow removing/adding controllers from/to cgroups > while there are tasks in them, which isn't safe unless we eliminate all > can_attach callbacks. We've done so for some cgroup subsystems, but > there are still a few of them... You can't remove can_attach(), we must be able to disallow joining a cgroup. If that results in you not being able to change the cgroup setup with tasks in, so be it -- that seems like a sane restriction anyhow.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> To: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Cc: Mike Galbraith <umgwanakikbuti-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> Subject: Re: [PATCH] sched: Relax a restriction in sched_rt_can_attach() Date: Mon, 4 May 2015 14:37:38 +0200 [thread overview] Message-ID: <20150504123738.GZ21418@twins.programming.kicks-ass.net> (raw) In-Reply-To: <554737AE.5040402-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> On Mon, May 04, 2015 at 05:11:10PM +0800, Zefan Li wrote: > Some degree of flexibility is provided so that you may disable some controllers > in a subtree. For example: > > root ---> child1 > (cpuset,memory,cpu) (cpuset,memory) > \ > \-> child2 > (cpu) Uhm, how does that work? Would a task their effective cgroup be the first parent that has a controller enabled? In particular, in your example, if T were part of child1, would its cpu controller be root? > I just realized we allow removing/adding controllers from/to cgroups > while there are tasks in them, which isn't safe unless we eliminate all > can_attach callbacks. We've done so for some cgroup subsystems, but > there are still a few of them... You can't remove can_attach(), we must be able to disallow joining a cgroup. If that results in you not being able to change the cgroup setup with tasks in, so be it -- that seems like a sane restriction anyhow.
next prev parent reply other threads:[~2015-05-04 12:38 UTC|newest] Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-04 0:54 [PATCH] sched: Relax a restriction in sched_rt_can_attach() Zefan Li 2015-05-04 0:54 ` Zefan Li 2015-05-04 3:13 ` Mike Galbraith 2015-05-04 3:13 ` Mike Galbraith 2015-05-04 4:39 ` Zefan Li 2015-05-04 4:39 ` Zefan Li 2015-05-04 5:10 ` Mike Galbraith 2015-05-04 5:10 ` Mike Galbraith 2015-05-04 5:39 ` Mike Galbraith 2015-05-04 5:39 ` Mike Galbraith 2015-05-04 9:11 ` Zefan Li 2015-05-04 9:11 ` Zefan Li 2015-05-04 12:08 ` Mike Galbraith 2015-05-04 12:08 ` Mike Galbraith 2015-05-04 12:37 ` Peter Zijlstra [this message] 2015-05-04 12:37 ` Peter Zijlstra 2015-05-04 14:09 ` Mike Galbraith 2015-05-05 3:46 ` Zefan Li 2015-05-05 3:46 ` Zefan Li 2015-05-05 6:02 ` Mike Galbraith 2015-05-05 6:02 ` Mike Galbraith 2015-05-05 3:54 ` Zefan Li 2015-05-05 3:54 ` Zefan Li 2015-05-05 14:10 ` Peter Zijlstra 2015-05-05 14:18 ` Tejun Heo 2015-05-05 15:19 ` Peter Zijlstra 2015-05-05 16:31 ` Tejun Heo 2015-05-05 19:00 ` Peter Zijlstra 2015-05-05 19:06 ` Tejun Heo 2015-05-05 19:06 ` Tejun Heo 2015-05-06 8:49 ` Peter Zijlstra 2015-05-06 8:49 ` Peter Zijlstra 2015-05-05 14:41 ` Tejun Heo 2015-05-05 15:11 ` Peter Zijlstra 2015-05-05 16:13 ` Tejun Heo 2015-05-05 16:50 ` Peter Zijlstra 2015-05-05 18:29 ` Thomas Gleixner 2015-05-05 19:00 ` Tejun Heo 2015-05-05 19:00 ` Tejun Heo 2015-05-06 9:12 ` Thomas Gleixner 2015-05-05 18:31 ` Tejun Heo 2015-05-05 14:09 ` Tejun Heo 2015-05-05 14:09 ` Tejun Heo
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