On Tue 24-02-15 14:54:01, Shaohua Li wrote: > On Tue, Feb 24, 2015 at 04:43:18PM +0100, Michal Hocko wrote: > > On Tue 24-02-15 17:18:14, Minchan Kim wrote: > > > Recently, Shaohua reported that MADV_FREE is much slower than > > > MADV_DONTNEED in his MADV_FREE bomb test. The reason is many of > > > applications went to stall with direct reclaim since kswapd's > > > reclaim speed isn't fast than applications's allocation speed > > > so that it causes lots of stall and lock contention. > > > > I am not sure I understand this correctly. So the issue is that there is > > huge number of MADV_FREE on the LRU and they are not close to the tail > > of the list so the reclaim has to do a lot of work before it starts > > dropping them? > > I thought the main reason is current reclaim stragety. Anonymous pages are > considered to be hard to be reclaimed with current policy, VM bias to reclaim > file pages (anon pages are in active list first, referenced pte will > reactivate > anon pages and increase rotate count)
Makes sense. We are really biasing to page cache reclaim most of the time. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
