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SubjectRe: [PATCH] mmtom: Prevent shrinking of active anon lru list in case of no swap space V2
Minchan Kim wrote:
> HI, Rik
>
> Thanks for careful review. :)
>
> On Thu, May 14, 2009 at 9:58 PM, Rik van Riel <riel@redhat.com> wrote:
>> Minchan Kim wrote:
>>
>>> Now shrink_active_list is called several places.
>>> But if we don't have a swap space, we can't reclaim anon pages.
>> If swap space has run out, get_scan_ratio() will return
>> 0 for the anon scan ratio, meaning we do not scan the
>> anon lists.
>
> I think get_scan_ration can't prevent scanning of anon pages in no
> swap system(like embedded system).
> That's because in shrink_zone, you add following as
>
> /*
> * Even if we did not try to evict anon pages at all, we want to
> * rebalance the anon lru active/inactive ratio.
> */
> if (inactive_anon_is_low(zone, sc))
> shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);

That's a fair point.

How about we change this to:

if (inactive_anon_is_low(zone, sc) && nr_swap_pages >= 0)

That way GCC will statically optimize away this branch on
systems with CONFIG_SWAP=n.

Does that look reasonable?

--
All rights reversed.


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