On Wed, Jul 03, 2019 at 04:30:57PM +0200, Michal Hocko wrote: > > How does the reclaim behave with workloads with file backed data set > not fitting into the memory? Aren't we going to to swap a lot - > something that the heuristic is protecting from? > In common case, most of the pages in a large file backed data set are non-executable. When there are a lot of non-executable file pages, usually more file pages are scanned because of the recent_scanned / recent_rotated ratio. I modified the test program to set the accessed sizes of the executable and non-executable file pages respectively. The test program runs on 2GB RAM VM with kernel 5.2.0-rc7 and this patch, allocates 2000 MB anonymous memory, then accesses 100 MB executable file pages and 2100 MB non-executable file pages for 10 times. The test also prints the file and anonymous page sizes in kB from /proc/meminfo. There are not too many swaps in this test case. I got similar test result without this patch. $ ./thrash 2000 100 2100 10 Allocate 2000 MB anonymous pages Active(anon): 1850964, Inactive(anon): 133140, Active(file): 1528, Inactive(file): 1352 Access 100 MB executable file pages Access 2100 MB regular file pages File access time, round 0: 26.833665 (sec) Active(anon): 1476084, Inactive(anon): 492060, Active(file): 2236, Inactive(file): 2224 File access time, round 1: 26.362102 (sec) Active(anon): 1471364, Inactive(anon): 490464, Active(file): 8508, Inactive(file): 8172 File access time, round 2: 26.828894 (sec) Active(anon): 1469184, Inactive(anon): 489688, Active(file): 10012, Inactive(file): 9840 File access time, round 3: 27.105603 (sec) Active(anon): 1468128, Inactive(anon): 489408, Active(file): 11000, Inactive(file): 10388 File access time, round 4: 26.936500 (sec) Active(anon): 1466380, Inactive(anon): 488788, Active(file): 12872, Inactive(file): 12504 File access time, round 5: 26.294687 (sec) Active(anon): 1466384, Inactive(anon): 488780, Active(file): 13332, Inactive(file): 12396 File access time, round 6: 27.382404 (sec) Active(anon): 1466344, Inactive(anon): 488772, Active(file): 13100, Inactive(file): 12276 File access time, round 7: 26.607976 (sec) Active(anon): 1466392, Inactive(anon): 488764, Active(file): 12892, Inactive(file): 11928 File access time, round 8: 26.477663 (sec) Active(anon): 1466344, Inactive(anon): 488760, Active(file): 12920, Inactive(file): 12092 File access time, round 9: 26.552859 (sec) Active(anon): 1465820, Inactive(anon): 488748, Active(file): 13300, Inactive(file): 12372
