From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org,
pjt-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
kernel-team-b10kYP2dOMg@public.gmane.org
Subject: Re: [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP
Date: Thu, 7 Apr 2016 12:42:59 +0200 [thread overview]
Message-ID: <20160407104259.GQ3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160407092824.GA13839-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
On Thu, Apr 07, 2016 at 05:28:24AM -0400, Johannes Weiner wrote:
> Hm? The root group can always contain tasks. It's not the only thing
> the root is exempt from, it can't control any resources either:
it does in fact control resouces; the hierarchy directly affects the
proportional distribution of time.
> sched_group_set_shares():
>
> /*
> * We can't change the weight of the root cgroup.
> */
> if (!tg->se[0])
> return -EINVAL;
The root has, per definition, no siblings, so setting a weight is
entirely pointless.
> tg_set_cfs_bandwidth():
>
> if (tg == &root_task_group)
> return -EINVAL;
>
We have had patches to implement this, but have so far held off because
they add a bunch of cycles to some really hot paths and we'd rather not
do that. Its not impossible, or unthinkable to do this otherwise.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
mingo@redhat.com, lizefan@huawei.com, pjt@google.com,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-api@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP
Date: Thu, 7 Apr 2016 12:42:59 +0200 [thread overview]
Message-ID: <20160407104259.GQ3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160407092824.GA13839@cmpxchg.org>
On Thu, Apr 07, 2016 at 05:28:24AM -0400, Johannes Weiner wrote:
> Hm? The root group can always contain tasks. It's not the only thing
> the root is exempt from, it can't control any resources either:
it does in fact control resouces; the hierarchy directly affects the
proportional distribution of time.
> sched_group_set_shares():
>
> /*
> * We can't change the weight of the root cgroup.
> */
> if (!tg->se[0])
> return -EINVAL;
The root has, per definition, no siblings, so setting a weight is
entirely pointless.
> tg_set_cfs_bandwidth():
>
> if (tg == &root_task_group)
> return -EINVAL;
>
We have had patches to implement this, but have so far held off because
they add a bunch of cycles to some really hot paths and we'd rather not
do that. Its not impossible, or unthinkable to do this otherwise.
next prev parent reply other threads:[~2016-04-07 10:42 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 15:41 [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 02/10] cgroup: un-inline cgroup_path() and friends Tejun Heo
2016-03-11 15:41 ` [PATCH 04/10] signal: make put_signal_struct() public Tejun Heo
2016-03-11 15:41 ` [PATCH 06/10] cgroup, fork: add @child and @clone_flags to threadgroup_change_begin/end() Tejun Heo
2016-03-11 15:41 ` [PATCH 09/10] cgroup: implement rgroup subtree migration Tejun Heo
[not found] ` <1457710888-31182-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-03-11 15:41 ` [PATCH 01/10] cgroup: introduce cgroup_[un]lock() Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 03/10] cgroup: introduce CGRP_MIGRATE_* flags Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 05/10] cgroup, fork: add @new_rgrp_cset[p] and @clone_flags to cgroup fork callbacks Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 07/10] cgroup: introduce resource group Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 08/10] cgroup: implement rgroup control mask handling Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 15:41 ` [PATCH 10/10] cgroup, sched: implement PRIO_RGRP for {set|get}priority() Tejun Heo
2016-03-11 15:41 ` Tejun Heo
2016-03-11 16:05 ` Example program for PRIO_RGRP Tejun Heo
2016-03-11 16:05 ` Tejun Heo
2016-03-12 6:26 ` [PATCHSET RFC cgroup/for-4.6] cgroup, sched: implement resource group and PRIO_RGRP Mike Galbraith
2016-03-12 6:26 ` Mike Galbraith
[not found] ` <1457764019.10402.72.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-03-12 17:04 ` Mike Galbraith
2016-03-12 17:04 ` Mike Galbraith
[not found] ` <1457802262.3628.129.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-03-12 17:13 ` cgroup NAKs ignored? " Ingo Molnar
2016-03-12 17:13 ` Ingo Molnar
[not found] ` <20160312171318.GD1108-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-03-13 14:42 ` Tejun Heo
2016-03-13 14:42 ` Tejun Heo
2016-03-13 15:00 ` Tejun Heo
2016-03-13 15:00 ` Tejun Heo
[not found] ` <20160313150012.GB13405-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-03-13 17:40 ` Mike Galbraith
2016-03-13 17:40 ` Mike Galbraith
[not found] ` <1457890835.3859.72.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-04-07 0:00 ` Tejun Heo
2016-04-07 0:00 ` Tejun Heo
[not found] ` <20160407000034.GL24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-07 3:26 ` Mike Galbraith
2016-04-07 3:26 ` Mike Galbraith
2016-03-14 2:23 ` Mike Galbraith
2016-03-14 2:23 ` Mike Galbraith
2016-03-14 11:30 ` Peter Zijlstra
2016-03-14 11:30 ` Peter Zijlstra
[not found] ` <20160314113013.GM6344-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-06 15:58 ` Tejun Heo
2016-04-06 15:58 ` Tejun Heo
2016-04-06 15:58 ` Tejun Heo
[not found] ` <20160406155830.GI24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-07 6:45 ` Peter Zijlstra
2016-04-07 6:45 ` Peter Zijlstra
[not found] ` <20160407064549.GH3430-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-07 7:35 ` Johannes Weiner
2016-04-07 7:35 ` Johannes Weiner
[not found] ` <20160407073547.GA12560-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2016-04-07 8:05 ` Mike Galbraith
2016-04-07 8:05 ` Mike Galbraith
2016-04-07 8:08 ` Peter Zijlstra
2016-04-07 8:08 ` Peter Zijlstra
[not found] ` <20160407080833.GK3430-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-07 9:28 ` Johannes Weiner
2016-04-07 9:28 ` Johannes Weiner
[not found] ` <20160407092824.GA13839-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2016-04-07 10:42 ` Peter Zijlstra [this message]
2016-04-07 10:42 ` Peter Zijlstra
2016-04-07 19:45 ` Tejun Heo
2016-04-07 19:45 ` Tejun Heo
[not found] ` <20160407194555.GI7822-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-04-07 20:25 ` Peter Zijlstra
2016-04-07 20:25 ` Peter Zijlstra
[not found] ` <20160407202542.GD3448-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-08 20:11 ` Tejun Heo
2016-04-08 20:11 ` Tejun Heo
[not found] ` <20160408201135.GO24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-09 6:16 ` Mike Galbraith
2016-04-09 6:16 ` Mike Galbraith
2016-04-09 13:39 ` Peter Zijlstra
2016-04-09 13:39 ` Peter Zijlstra
[not found] ` <20160409133917.GV3448-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-12 22:29 ` Tejun Heo
2016-04-12 22:29 ` Tejun Heo
[not found] ` <20160412222915.GT24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-13 7:43 ` Mike Galbraith
2016-04-13 7:43 ` Mike Galbraith
2016-04-13 15:59 ` Tejun Heo
[not found] ` <20160413155952.GU24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-13 19:15 ` Mike Galbraith
2016-04-13 19:15 ` Mike Galbraith
2016-04-14 6:07 ` Mike Galbraith
[not found] ` <1460614057.5100.150.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-04-14 19:57 ` Tejun Heo
2016-04-14 19:57 ` Tejun Heo
[not found] ` <20160414195748.GK7822-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-04-15 2:42 ` Mike Galbraith
2016-04-15 2:42 ` Mike Galbraith
2016-04-09 16:02 ` Peter Zijlstra
2016-04-09 16:02 ` Peter Zijlstra
2016-04-07 8:28 ` Peter Zijlstra
2016-04-07 8:28 ` Peter Zijlstra
[not found] ` <20160407082810.GN3430-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-07 19:04 ` Johannes Weiner
2016-04-07 19:04 ` Johannes Weiner
[not found] ` <20160407190424.GA20407-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2016-04-07 19:31 ` Peter Zijlstra
2016-04-07 19:31 ` Peter Zijlstra
[not found] ` <20160407193127.GB3448-ndre7Fmf5hadTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2016-04-07 20:23 ` Johannes Weiner
2016-04-07 20:23 ` Johannes Weiner
[not found] ` <20160407202344.GA22509-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2016-04-08 3:13 ` Mike Galbraith
2016-04-08 3:13 ` Mike Galbraith
2016-03-15 17:21 ` Michal Hocko
2016-03-15 17:21 ` Michal Hocko
[not found] ` <20160315172136.GA6114-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2016-04-06 21:53 ` Tejun Heo
2016-04-06 21:53 ` Tejun Heo
[not found] ` <20160406215307.GJ24661-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-04-07 6:40 ` Peter Zijlstra
2016-04-07 6:40 ` Peter Zijlstra
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