Messages in this thread | | | Subject | Re: Still OOM problems with 4.9er/4.10er kernels | From | Gerhard Wiesinger <> | Date | Fri, 17 Mar 2017 17:37:48 +0100 |
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On 16.03.2017 10:39, Michal Hocko wrote: > On Thu 16-03-17 02:23:18, lkml@pengaru.com wrote: >> On Thu, Mar 16, 2017 at 10:08:44AM +0100, Michal Hocko wrote: >>> On Thu 16-03-17 01:47:33, lkml@pengaru.com wrote: >>> [...] >>>> While on the topic of understanding allocation stalls, Philip Freeman recently >>>> mailed linux-kernel with a similar report, and in his case there are plenty of >>>> page cache pages. It was also a GFP_HIGHUSER_MOVABLE 0-order allocation. >>> care to point me to the report? >> http://lkml.iu.edu/hypermail/linux/kernel/1703.1/06360.html > Thanks. It is gone from my lkml mailbox. Could you CC me (and linux-mm) please? > >>> >>>> I'm no MM expert, but it appears a bit broken for such a low-order allocation >>>> to stall on the order of 10 seconds when there's plenty of reclaimable pages, >>>> in addition to mostly unused and abundant swap space on SSD. >>> yes this might indeed signal a problem. >> Well maybe I missed something obvious that a better informed eye will catch. > Nothing really obvious. There is indeed a lot of anonymous memory to > swap out. Almost no pages on file LRU lists (active_file:759 > inactive_file:749) but 158783 total pagecache pages so we have to have a > lot of pages in the swap cache. I would probably have to see more data > to make a full picture. >
Why does the kernel prefer to swapin/out and not use
a.) the free memory?
b.) the buffer/cache?
There is ~100M memory available but kernel swaps all the time ...
Any ideas?
Kernel: 4.9.14-200.fc25.x86_64
top - 17:33:43 up 28 min, 3 users, load average: 3.58, 1.67, 0.89 Tasks: 145 total, 4 running, 141 sleeping, 0 stopped, 0 zombie %Cpu(s): 19.1 us, 56.2 sy, 0.0 ni, 4.3 id, 13.4 wa, 2.0 hi, 0.3 si, 4.7 st KiB Mem : 230076 total, 61508 free, 123472 used, 45096 buff/cache
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 3 5 303916 60372 328 43864 27828 200 41420 236 6984 11138 11 47 6 23 14 5 4 292852 52904 756 58584 19600 448 48780 540 8088 10528 18 61 1 7 13 3 3 288792 49052 1152 65924 4856 576 9824 1100 4324 5720 7 18 2 64 8 2 2 283676 54160 716 67604 6332 344 31740 964 3879 5055 12 34 10 37 7 3 3 286852 66712 216 53136 28064 4832 56532 4920 9175 12625 10 55 12 14 10 2 0 299680 62428 196 53316 36312 13164 54728 13212 16820 25283 7 56 18 12 7 1 1 300756 63220 624 58160 17944 1260 24528 1304 5804 9302 3 22 38 34 3
Thnx.
Ciao,
Gerhard
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