[Devel] Re: [PATCH -mmotm 0/4] memcg: per cgroup dirty limit (v4)

[Balbir Singh]

* Andrea Righi <arighi at develer.com> [2010-03-04 11:40:11]:

> Control the maximum amount of dirty pages a cgroup can have at any given time.
> 
> Per cgroup dirty limit is like fixing the max amount of dirty (hard to reclaim)
> page cache used by any cgroup. So, in case of multiple cgroup writers, they
> will not be able to consume more than their designated share of dirty pages and
> will be forced to perform write-out if they cross that limit.
> 
> The overall design is the following:
> 
>  - account dirty pages per cgroup
>  - limit the number of dirty pages via memory.dirty_ratio / memory.dirty_bytes
>    and memory.dirty_background_ratio / memory.dirty_background_bytes in
>    cgroupfs
>  - start to write-out (background or actively) when the cgroup limits are
>    exceeded
> 
> This feature is supposed to be strictly connected to any underlying IO
> controller implementation, so we can stop increasing dirty pages in VM layer
> and enforce a write-out before any cgroup will consume the global amount of
> dirty pages defined by the /proc/sys/vm/dirty_ratio|dirty_bytes and
> /proc/sys/vm/dirty_background_ratio|dirty_background_bytes limits.
> 
> Changelog (v3 -> v4)
> ~~~~~~~~~~~~~~~~~~~~~~
>  * handle the migration of tasks across different cgroups
>    NOTE: at the moment we don't move charges of file cache pages, so this
>    functionality is not immediately necessary. However, since the migration of
>    file cache pages is in plan, it is better to start handling file pages
>    anyway.
>  * properly account dirty pages in nilfs2
>    (thanks to Kirill A. Shutemov <kirill at shutemov.name>)
>  * lockless access to dirty memory parameters
>  * fix: page_cgroup lock must not be acquired under mapping->tree_lock
>    (thanks to Daisuke Nishimura <nishimura at mxp.nes.nec.co.jp> and
>     KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>)
>  * code restyling
>

This seems to be converging, what sort of tests are you running on
this patchset? 

-- 
	Three Cheers,
	Balbir
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