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SubjectRe: Still OOM problems with 4.9er/4.10er kernels
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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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