> Can you provide (a single snapshot) /proc/pagetypeinfo and > /proc/slabinfo from a system that's currently experiencing the issue, > also with /proc/vmstat and /proc/zoneinfo to verify? Thanks. your request came in just one day after I 2>drop_caches again when the ram usage was really really low again. Up until now it did not reoccur on any of the 2 hosts, where one shows 550MB/11G with 37G of totally free ram for now - so not that low like last time when I dropped it, I think it was like 300M/8G or so, but I hope it helps: /proc/pagetypeinfo https://pastebin.com/6QWEZagL /proc/slabinfo https://pastebin.com/81QAFgke /proc/vmstat https://pastebin.com/S7mrQx1s /proc/zoneinfo https://pastebin.com/csGeqNyX also please note - whether this makes any difference: there is no swap file/partition I am using this without swap space. imho this should not be necessary since applications running on the hosts would not consume more than 20GB, the rest should be used by buffers/cache. 2018-07-30 16:40 GMT+02:00 Michal Hocko : > On Fri 27-07-18 13:15:33, Vlastimil Babka wrote: > > On 07/21/2018 12:03 AM, Marinko Catovic wrote: > > > I let this run for 3 days now, so it is quite a lot, there you go: > > > https://nofile.io/f/egGyRjf0NPs/vmstat.tar.gz > > > > The stats show that compaction has very bad results. Between first and > > last snapshot, compact_fail grew by 80k and compact_success by 1300. > > High-order allocations will thus cycle between (failing) compaction and > > reclaim that removes the buffer/caches from memory. > > I guess you are right. I've just looked at random large direct reclaim > activity > $ grep -w pgscan_direct vmstat*| awk '{diff=$2-old; if (old && diff > > 100000) printf "%s %d\n", $1, diff; old=$2}' > vmstat.1531957422:pgscan_direct 114334 > vmstat.1532047588:pgscan_direct 111796 > > $ paste-with-diff.sh vmstat.1532047578 vmstat.1532047588 | grep > "pgscan\|pgsteal\|compact\|pgalloc" | sort > # counter value1 value2-value1 > compact_daemon_free_scanned 2628160139 0 > compact_daemon_migrate_scanned 797948703 0 > compact_daemon_wake 23634 0 > compact_fail 124806 108 > compact_free_scanned 226181616304 295560271 > compact_isolated 2881602028 480577 > compact_migrate_scanned 147900786550 27834455 > compact_stall 146749 108 > compact_success 21943 0 > pgalloc_dma 0 0 > pgalloc_dma32 1577060946 10752 > pgalloc_movable 0 0 > pgalloc_normal 29389246430 343249 > pgscan_direct 737335028 111796 > pgscan_direct_throttle 0 0 > pgscan_kswapd 1177909394 0 > pgsteal_direct 704542843 111784 > pgsteal_kswapd 898170720 0 > > There is zero kswapd activity so this must have been higher order > allocation activity and all the direct compaction failed so we keep > reclaiming. > -- > Michal Hocko > SUSE Labs >