Messages in this thread | | | From | Satoru Moriya <> | Date | Fri, 20 Apr 2012 20:21:28 -0400 | Subject | RE: [RFC][PATCH] avoid swapping out with swappiness==0 |
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Hi,
Sorry for my late reply.
On 04/04/2012 01:38 PM, KOSAKI Motohiro wrote: > (4/3/12 4:25 AM), Jerome Marchand wrote: >> On 04/02/2012 07:10 PM, KOSAKI Motohiro wrote: >>> 2012/3/30 Satoru Moriya<satoru.moriya@hds.com>: >>>> So the kernel reclaims pages like following. >>>> >>>> nr_free + nr_filebacked>= watermark_high: reclaim only filebacked pages >>>> nr_free + nr_filebacked< watermark_high: reclaim only anonymous pages >>> >>> How? >> >> get_scan_count() checks that case explicitly: >> >> if (global_reclaim(sc)) { >> free = zone_page_state(mz->zone, NR_FREE_PAGES); >> /* If we have very few page cache pages, >> force-scan anon pages. */ >> if (unlikely(file + free<= high_wmark_pages(mz->zone))) { >> fraction[0] = 1; >> fraction[1] = 0; >> denominator = 1; >> goto out; >> } >> } > > Eek. This is silly. Nowaday many people enabled THP and it increase zone watermark. > so, high watermask is not good threshold anymore.
Ah yes, it is not so small now. On 4GB server, without THP min_free_kbytes is 8113 but with THP it is 67584.
How about using low watermark or min watermark? Are they still big?
...or should we use other value?
Regards, Satoru
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