Re: [v5][PATCH 6/6] mm: vmscan: drain batch list during longoperations

[Minchan Kim]

On Mon, Jun 03, 2013 at 01:02:10PM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> This was a suggestion from Mel:
> 
> 	http://lkml.kernel.org/r/20120914085634.GM11157@xxxxxxxxx
> 
> Any pages we collect on 'batch_for_mapping_removal' will have
> their lock_page() held during the duration of their stay on the
> list.  If some other user is trying to get at them during this
> time, they might end up having to wait.
> 
> This ensures that we drain the batch if we are about to perform a
> pageout() or congestion_wait(), either of which will take some
> time.  We expect this to help mitigate the worst of the latency
> increase that the batching could cause.

Nice idea but I could see drain before pageout but congestion_wait?

-- 
Kind regards,
Minchan Kim
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