On Mon, Aug 6, 2012 at 11:51 AM, Rik van Riel <riel@xxxxxxxxxx> wrote: > On 08/06/2012 11:11 AM, Michal Hocko wrote: >> >> On Mon 06-08-12 10:27:25, Rik van Riel wrote: > > >>>> So you think we shouldn't do the full round over memcgs in shrink_zone a >>>> and rather do it oom way to pick up a victim and hammer it? >>> >>> >>> Not hammer it too far. Only until its score ends up well >>> below (25% lower?) than that of the second highest scoring >>> list. >>> >>> That way all the lists get hammered a little bit, in turn. >> >> >> How do we provide the soft limit guarantee then? >> >> [...] > > > The easiest way would be to find the top 2 or 3 scoring memcgs > when we reclaim memory. After reclaiming some pages, recalculate > the scores of just these top lists, and see if the list we started > out with now has a lower score than the second one. > > Once we have reclaimed some from each of the 2 or 3 lists, we can > go back and find the highest priority lists again. Sounds like quite a lot of calculation to pick which memcg to reclaim from, and I wonder if that is necessary at all. For most of the use cases, we don't need to pick the lowest score memcg to reclaim from first. My understanding is that if we can respect the (lru_size - softlimit) to calculate the nr_to_scan, that is good move from what we have today. If so, can we just still do the round-robin fashion in shrink_zone() and for each memcg, we calculate the nr_to_scan similar to get_scan_count() what have today but w/ the new formula. For memcg under its softlimit, we avoid reclaim pages unless no more pages can be reclaimed, and then we start reclaiming under the softlimit. That part can use the same logic depending on (softlimit - lru_size) --Ying Can we do something similar to the > > Direct reclaim only reclaims a little bit at a time, anyway. > > For kswapd, we could also remember the number of pages the group > has in excess of its soft limit, and recalculate after that... > > -- > All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>