[PATCH 1/8] cgroup: add cgroup->id

Tejun Heo tj at kernel.org
Tue Nov 20 07:08:51 UTC 2012


Hello, Kamezawa.

On Tue, Nov 20, 2012 at 04:05:51PM +0900, Kamezawa Hiroyuki wrote:
> BTW, css's ID was limited to 65535 to be encoded in 2bytes.
> If we use INT, this will increase size of swap_cgroup.
> (2bytes per page => 4bytes per page) It's preallocated at swapon()
> because allocating memory dynamically when we swap a memory is not good.
> 
> Do we really need 4bytes for ID ? If so, swap_cgroup should be totally re-designed.

That's a memcg restriction which shouldn't have been imposed on cgroup
core from the beginning.  What memcg should do is rejecting to become
online from ->css_onilne() if cgrp->id is out of the range it can
handle.

Thanks.

-- 
tejun


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