Re: [PATCH 2/8] mm: Remove i_mmap_mutex lockbreak

[KAMEZAWA Hiroyuki]

On Thu, 17 Feb 2011 18:05:22 +0100
Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:

> Hugh says:
>  "The only significant loser, I think, would be page reclaim (when
>   concurrent with truncation): could spin for a long time waiting for
>   the i_mmap_mutex it expects would soon be dropped? "
> 
> Counter points:
>  - cpu contention makes the spin stop (need_resched())
>  - zap pages should be freeing pages at a higher rate than reclaim
>    ever can
>  - shouldn't hold up reclaim more than lock_page() would
> 
> I think the simplification of the truncate code is definately worth
> it.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

Maybe I have to improve batched-uncharge in memcg, whose work depends
on ZAP_BLOCK_SIZE....but the zap routine seems cleaner.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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