Re: [PATCH -mmotm 0/7] memcg: move charge at task migration (04/Dec)

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Fri, 4 Dec 2009 14:46:09 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> Hi.
> 
> These are current patches of my move-charge-at-task-migration feature.
> 
> The biggest change from previous(19/Nov) version is improvement in performance.
> 
> I measured the elapsed time of "echo [pid] > <some path>/tasks" on KVM guest
> with 4CPU/4GB(Xeon/3GHz) in three patterns:
> 
>   (1) / -> /00
>   (2) /00 -> /01
> 
>   we don't need to call res_counter_uncharge against root, so (1) would be smaller
>   than (2).
> 
>   (3) /00(setting mem.limit to half size of total) -> /01
> 
>   To compare the overhead of anon and swap.
> 
> In 19/Nov version:
>        |  252M  |  512M  |   1G
>   -----+--------+--------+--------
>    (1) |  0.21  |  0.41  |  0.821
>   -----+--------+--------+--------
>    (2) |  0.43  |  0.85  |  1.71
>   -----+--------+--------+--------
>    (3) |  0.40  |  0.81  |  1.62
>   -----+--------+--------+--------
> 
> In this version:
>        |  252M  |  512M  |   1G
>   -----+--------+--------+--------
>    (1) |  0.15  |  0.30  |  0.60
>   -----+--------+--------+--------
>    (2) |  0.15  |  0.30  |  0.60
>   -----+--------+--------+--------
>    (3) |  0.22  |  0.44  |  0.89
> 
Nice !

> Please read patch descriptions for each patch([4/7],[7/7]) for details of
> how and how much the patch improved the performance.
> 
>   [1/7] cgroup: introduce cancel_attach()
>   [2/7] memcg: add interface to move charge at task migration
>   [3/7] memcg: move charges of anonymous page
>   [4/7] memcg: improbe performance in moving charge
>   [5/7] memcg: avoid oom during moving charge
>   [6/7] memcg: move charges of anonymous swap
>   [7/7] memcg: improbe performance in moving swap charge
> 
> Current version supports only recharge of non-shared(mapcount == 1) anonymous pages
> and swaps of those pages. I think it's enough as a first step.
> 
Hmm. shared swap entry (very rare one?) is moved ?

Thanks,
-Kame


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