Re: [PATCH] vmscan: bail out of page reclaim after swap_cluster_max pages

From: KOSAKI Motohiro
Date: Tue Nov 25 2008 - 06:35:27 EST


> Sometimes the VM spends the first few priority rounds rotating back
> referenced pages and submitting IO. Once we get to a lower priority,
> sometimes the VM ends up freeing way too many pages.
>
> The fix is relatively simple: in shrink_zone() we can check how many
> pages we have already freed, direct reclaim tasks break out of the
> scanning loop if they have already freed enough pages and have reached
> a lower priority level.
>
> However, in order to do this we do need to know how many pages we already
> freed, so move nr_reclaimed into scan_control.
>
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
> ---
> Kosaki, this should address the zone scanning pressure issue.

hmmmm. I still don't like the behavior when priority==DEF_PRIORITY.
but I also should explain by code and benchmark.

therefore, I'll try to mesure this patch in this week.

thanks.


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