21 Oct
2020
21 Oct
'20
08:54
https://bugzilla.suse.com/show_bug.cgi?id=1159882 https://bugzilla.suse.com/show_bug.cgi?id=1159882#c84 --- Comment #84 from Michal Hocko--- Sorry for a late reply. I was busy with other issues (In reply to Robert Delahunt from comment #75) > In about five minutes: > > This is with vmstats with your kernel with cgroups enabled: > > http://www.puresimplicity.net/~delahunt/vmstat/mhocko4/ diff between the first and last snapshot 1602004484 1602004607[diff] pswpin 0 0 pswpout 0 48703 pgscan_kswapd 0 7177411 pgscan_direct 0 0 pgsteal_kswapd 0 7115294 pgsteal_direct 0 0 > This is with vmstats with your kernel with cgroups disabled: > > http://www.puresimplicity.net/~delahunt/vmstat/mhocko5/ 1602004764 1602004958[diff] pswpin 0 0 pswpout 0 75781 pgscan_kswapd 0 13728122 pgscan_direct 0 0 pgsteal_kswapd 0 13664819 pgsteal_direct 0 0 Both do swap out. The later covers a longer time period - 194s vs 123s and scans twice as many pages which results in twice as many pages reclaimed and 55% more swapout. >From that we can conclude (from a high level) that the swapout reflects the overall reclaim and cgroups enabled/disabled doesn't play any major role here. Which is a good confirmation because it would be really curious to see a difference in the behavior just from having cgroups enabled without being used. So let's focus on the cgroups enabled case for now. Let's have a look at 1602004840 1602004841[diff] pswpin 0 0 pswpout 3103 6801 pgsteal_kswapd 206006 148891 pgscan_kswapd 251736 148891 nr_active_anon 339953 -1840 nr_active_file 147150 7 nr_inactive_anon 38139 9382 nr_inactive_file 7263922 -2703 workingset_activate 170 0 workingset_refault 170 57 workingset_restore 0 0 >From this we can conclude that - some active anonymous pages have been rotated to the inactive list which grown much larger though - even when we consider the swapout. So there must be some process allocating a nontrivial amount of anonymous memory and there is more going on than just the IO test case - There is a ton of inactive page cache to reclaim from - refaults are quite marginal So this is in line with previous observations. I am inclined to drop the two patches mentioned earlier (comment 60) as they are known to contribute considerably. Unless Vlastimil or Mel speak up. At this moment I am not sure how much more time I can spend on this so I would recommend to use a more recent kernel. Btw. considering stalls. The data I have seen so far doesn't indicate any reclaim induced source of a potential stall. There is no swap in neither no direct reclaim. So existing reclaim decisions. Maybe in your regular workload there is a considerable swapin (pswpin) going on. -- You are receiving this mail because: You are the assignee for the bug.