From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: lizefan@huawei.com, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, hannes@cmpxchg.org, mhocko@suse.cz,
axboe@kernel.dk
Subject: Re: [PATCH v2 6/6] blkcg, memcg: make blkcg depend on memcg on the default hierarchy
Date: Tue, 8 Jul 2014 17:53:51 -0400 [thread overview]
Message-ID: <20140708215351.GJ4979@htj.dyndns.org> (raw)
In-Reply-To: <20140708194226.GA18382@redhat.com>
Hello, Vivek.
On Tue, Jul 08, 2014 at 03:42:26PM -0400, Vivek Goyal wrote:
> I have couple questions about new semantics. Following is my
> understanding. Is it right?
>
> - So after this change one can not use blkio controller on unified
> hiearchy if memory controller is mounted on some other hierarchy
> and is not available for mounting unified hiearchy.
Hmmm? No, the only behavior which changes is when both blkcg and
memcg are mounted on the unified hierarchy. Nothing else changes.
The dependency behavior kicks in iff memcg is available on the unified
hierarchy.
> - If blkio controller is enabled on unified hiearchy (memory controller
> implicitly enabled), then one can't mount memory controller on other
> hierarchies without first disabling blkio controller on unified hiearchy.
Yes, blkio needs to be disabled to the root for memcg to be able to
become free. This is an extra restriction but I don't think it's
anything drastic. Once a controller starts being actively used on any
hierarchy, nothing has been guaranteed about when the controller would
become free again even if the whole hierarchy is reduced to the root.
Thanks.
--
tejun
next prev parent reply other threads:[~2014-07-08 21:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-28 1:03 [PATCHSET cgroup/for-3.17] cgroup, blkcg, memcg: make blkcg depend on memcg on unified hierarchy Tejun Heo
2014-06-28 1:03 ` [PATCH 1/6] cgroup: reorganize cgroup_subtree_control_write() Tejun Heo
2014-06-28 1:03 ` [PATCH 2/6] cgroup: introduce cgroup->subtree_control Tejun Heo
2014-06-28 1:03 ` [PATCH 3/6] cgroup: make interface files visible iff enabled on cgroup->subtree_control Tejun Heo
2014-06-28 1:03 ` [PATCH 4/6] cgroup: implement cgroup_subsys->css_reset() Tejun Heo
2014-06-28 1:03 ` [PATCH 5/6] cgroup: implement cgroup_subsys->depends_on Tejun Heo
2014-06-28 1:03 ` [PATCH 6/6] blkcg, memcg: make blkcg depend on memcg on the default hierarchy Tejun Heo
2014-06-28 11:49 ` [PATCH v2 " Tejun Heo
2014-07-08 19:42 ` Vivek Goyal
2014-07-08 21:53 ` Tejun Heo [this message]
2014-07-09 11:57 ` Vivek Goyal
2014-07-04 6:29 ` [PATCHSET cgroup/for-3.17] cgroup, blkcg, memcg: make blkcg depend on memcg on unified hierarchy Li Zefan
2014-07-07 18:33 ` Johannes Weiner
2014-07-08 22:03 ` Tejun Heo
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