Re: [PATCHSET] cgroup: cftype based file interface, take #2
From: Li Zefan
Date: Fri Mar 30 2012 - 08:46:38 EST
Tejun Heo wrote:
> This is the second take at improving cgroup file addition/removal
> interface. Changes from the last take[L] are,
> * CGROUP_SUBSYS_CFTYPES[_COND]() dropped and
> cgroup_subsys->base_cftypes is added instead. This works better for
> subsystems implemented as module. tcp_memcontrol now uses an
> explicit __initcall() to register its cftypes.
> * 0005-cgroup-relocate-cftype-and-cgroup_subsys-definitions.patch
> added as cleanup.
> * 0007-memcg-always-create-memsw-files-if-CONFIG_CGROUP_MEM.patch
> added so that memsw files are always created if enabled in config as
> suggested by KAMEZAWA.
> This patch replaces cgroup file interface with cftype based one which
> allows dynamic additions and removals of cftype arrays whether the
> target subsystem is attached or not. This can be used to make subsys
> rebinding via remount work properly but I intentionally avoided doing
> that at the moment.
What's the problem with remount? and is it important enough that it
should be fixed even the feature is marked as deprecated?
> This makes cgroup population simpler for controllers and will be used
> to allow controllers to be more dynamic. e.g. blkio subsys has
> sub-policies which may come and go while blkio subsys is attached and
> it currently uses fixed set of files which stays blank if not in use.
Dynamic cgroup files was mentioned before. The scenario in mind was blkio
control files can be added/removed automatically as devices come and ago.
So this time blkio subsystem is really going to be made more dynamic
> This will also be useful for implementing unified hierarchy.
> This patchset contains the following patches.
I'll look into the patches tomorrow.
> and is on top of
> cgroup/for-3.4 3ce3230a0cff484e5130153f244d4fb8a56b3a8b
> +  cgroup: deprecate remount option changes mount option
> and is also available in the following git branch.
> git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git cgroup-cftype
> Glauber, I think the cftypes registration for tcp_memcontrol is fine
> as is in this patchset and we just need to move the init to the tail
> of ->create(). Let's worry about memcg for module-loadable protocols
> whey they are added. Can you please send a patch to move init to
> If nobody objects && after Li comes back and acks the changes, I'll
> route these through cgroup/for-3.5.
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