Messages in this thread | | | Date | Wed, 27 Apr 2011 18:14:56 +0900 | Subject | Re: [PATCHv3] memcg: fix get_scan_count for small targets | From | Minchan Kim <> |
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On Wed, Apr 27, 2011 at 5:48 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > On Wed, 27 Apr 2011 17:48:18 +0900 > Minchan Kim <minchan.kim@gmail.com> wrote: > >> On Wed, Apr 27, 2011 at 4:47 PM, KAMEZAWA Hiroyuki >> <kamezawa.hiroyu@jp.fujitsu.com> wrote: >> > At memory reclaim, we determine the number of pages to be scanned >> > per zone as >> > (anon + file) >> priority. >> > Assume >> > scan = (anon + file) >> priority. >> > >> > If scan < SWAP_CLUSTER_MAX, the scan will be skipped for this time >> > and priority gets higher. This has some problems. >> > >> > 1. This increases priority as 1 without any scan. >> > To do scan in this priority, amount of pages should be larger than 512M. >> > If pages>>priority < SWAP_CLUSTER_MAX, it's recorded and scan will be >> > batched, later. (But we lose 1 priority.) >> > If memory size is below 16M, pages >> priority is 0 and no scan in >> > DEF_PRIORITY forever. >> > >> > 2. If zone->all_unreclaimabe==true, it's scanned only when priority==0. >> > So, x86's ZONE_DMA will never be recoverred until the user of pages >> > frees memory by itself. >> > >> > 3. With memcg, the limit of memory can be small. When using small memcg, >> > it gets priority < DEF_PRIORITY-2 very easily and need to call >> > wait_iff_congested(). >> > For doing scan before priorty=9, 64MB of memory should be used. >> > >> > Then, this patch tries to scan SWAP_CLUSTER_MAX of pages in force...when >> > >> > 1. the target is enough small. >> > 2. it's kswapd or memcg reclaim. >> > >> > Then we can avoid rapid priority drop and may be able to recover >> > all_unreclaimable in a small zones. And this patch removes nr_saved_scan. >> > This will allow scanning in this priority even when pages >> priority >> > is very small. >> > >> > Changelog v2->v3 >> > - removed nr_saved_scan completely. >> > >> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> >> >> The patch looks good to me but I have a nitpick about just coding style. >> How about this? I think below looks better but it's just my private >> opinion and I can't insist on my style. If you don't mind it, ignore. >> > > I did this at the 1st try and got bug.....a variable 'file' here is > reused and now broken. Renaming it with new variable will be ok, but it
Right you are. I missed that. :) Thanks.
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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