Messages in this thread | | | Date | Wed, 21 Jul 2010 08:03:09 +0900 | Subject | Re: [PATCH 4/8] Shrink zcache based on memlimit | From | Minchan Kim <> |
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Hi,
On Fri, Jul 16, 2010 at 9:37 PM, Nitin Gupta <ngupta@vflare.org> wrote: > User can change (per-pool) memlimit using sysfs node: > /sys/kernel/mm/zcache/pool<id>/memlimit > > When memlimit is set to a value smaller than current > number of pages allocated for that pool, excess pages > are now freed immediately instead of waiting for get/ > flush for these pages. > > Currently, victim page selection is essentially random. > Automatic cache resizing and better page replacement > policies will be implemented later.
Okay. I know this isn't end. I just want to give a concern before you end up. I don't know how you implement reclaim policy. In current implementation, you use memlimit for determining when reclaim happen. But i think we also should follow global reclaim policy of VM. I means although memlimit doen't meet, we should reclaim zcache if system has a trouble to reclaim memory. AFAIK, cleancache doesn't give any hint for that. so we should implement it in zcache itself. At first glance, we can use shrink_slab or oom_notifier. But both doesn't give any information of zone although global reclaim do it by per-zone. AFAIK, Nick try to implement zone-aware shrink slab. Also if we need it, we can change oom_notifier with zone-aware oom_notifier. Now it seems anyone doesn't use oom_notifier so I am not sure it's useful.
It's just my opinion. Thanks for effort for good feature. Nitin. -- Kind regards, Minchan Kim
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