Comment # 52 on bug 1159882 from Michal Hocko

(In reply to Robert Delahunt from comment #51)
> http://www.puresimplicity.net/~delahunt/vmstat/mhock/
> 
> Like I said, the vmstats after the time delay. They are in this directory.

I've misunderstood your comment. Anyway.
The system has started swapout at 1600908544 until 1600908551 to grow to 10194
and stayed there for some time for some time to repeat a similar pattern.
                     vmstat.1600908545       vmstat.1600908546 [diff]
nr_active_anon       200295                  -1660
nr_active_file       126906                  6879
nr_inactive_anon     35519                   7892
nr_inactive_file     3524850                -5187
nr_dirty             27282                  -18238
pswpout              271                    6282
workingset_activate  146                    19
workingset_refault   146                    19

So in overall numbers a huge amount of clean page cache. There are some
refaults and all of them are eve activations. But the number is still very
small to the actual page cache in general.

pgscan_kswapd         59636                  48139
pgsteal_kswapd        34126                  41061
pgscan_direct         0                      0

kswapd has relcaim 41k pages but let me outline that the overall number of
anonymous pages has increased in total. So it is not just the streaming IO that
is going on. We know that ~15% of the reclaimed memory was anonymous (and
swapped out) the rest must have been the page cache. If this was fully
proportional (swappiness) then the percentage would be different. So I suspect
that there is still a prevalent pagecache only reclaim happening with some
occasional runs based by refault information. We also age the anonymous active
list quite a lot but that shouldn't really lead to swapout on its own. It
however points a finger to 2c012a4ad1a2c.

I haven't checked the full data set. It would be worth having another test with
2c012a4ad1a2c reverted before we spend more time on the data. I will upload a
new kernel to the same location. Please note that the new kernel will have a
different release number (bsc1159882_2).