From: Gerhard Wiesinger <lists@wiesinger.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: lkml@pengaru.com, Minchan Kim <minchan@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Still OOM problems with 4.9er/4.10er kernels
Date: Fri, 17 Mar 2017 21:08:31 +0100 [thread overview]
Message-ID: <8cb1d796-aff3-0063-3ef8-880e76d437c0@wiesinger.com> (raw)
In-Reply-To: <20170317171339.GA23957@dhcp22.suse.cz>
On 17.03.2017 18:13, Michal Hocko wrote:
> On Fri 17-03-17 17:37:48, Gerhard Wiesinger wrote:
> [...]
>> Why does the kernel prefer to swapin/out and not use
>>
>> a.) the free memory?
> It will use all the free memory up to min watermark which is set up
> based on min_free_kbytes.
Makes sense, how is /proc/sys/vm/min_free_kbytes default value calculated?
>
>> b.) the buffer/cache?
> the memory reclaim is strongly biased towards page cache and we try to
> avoid swapout as much as possible (see get_scan_count).
If I understand it correctly, swapping is preferred over dropping the
cache, right. Can this behaviour be changed to prefer dropping the cache
to some minimum amount?
Is this also configurable in a way?
(As far as I remember e.g. kernel 2.4 dropped the caches well).
>
>> 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
> I am really surprised to see any reclaim at all. 26% of free memory
> doesn't sound as if we should do a reclaim at all. Do you have an
> unusual configuration of /proc/sys/vm/min_free_kbytes ? Or is there
> anything running inside a memory cgroup with a small limit?
nothing special set regarding /proc/sys/vm/min_free_kbytes (default
values), detailed config below. Regarding cgroups, none of I know. How
to check (I guess nothing is set because cg* commands are not available)?
cat /etc/sysctl.d/* | grep "^vm"
vm.dirty_background_ratio = 3
vm.dirty_ratio = 15
vm.overcommit_memory = 2
vm.overcommit_ratio = 80
vm.swappiness=10
find /proc/sys/vm -type f -exec echo {} \; -exec cat {} \;
/proc/sys/vm/admin_reserve_kbytes
8192
/proc/sys/vm/block_dump
0
/proc/sys/vm/compact_memory
cat: /proc/sys/vm/compact_memory: Permission denied
/proc/sys/vm/compact_unevictable_allowed
1
/proc/sys/vm/dirty_background_bytes
0
/proc/sys/vm/dirty_background_ratio
3
/proc/sys/vm/dirty_bytes
0
/proc/sys/vm/dirty_expire_centisecs
3000
/proc/sys/vm/dirty_ratio
15
/proc/sys/vm/dirty_writeback_centisecs
500
/proc/sys/vm/dirtytime_expire_seconds
43200
/proc/sys/vm/drop_caches
0
/proc/sys/vm/extfrag_threshold
500
/proc/sys/vm/hugepages_treat_as_movable
0
/proc/sys/vm/hugetlb_shm_group
0
/proc/sys/vm/laptop_mode
0
/proc/sys/vm/legacy_va_layout
0
/proc/sys/vm/lowmem_reserve_ratio
256 256 32 1
/proc/sys/vm/max_map_count
65530
/proc/sys/vm/memory_failure_early_kill
0
/proc/sys/vm/memory_failure_recovery
1
/proc/sys/vm/min_free_kbytes
45056
/proc/sys/vm/min_slab_ratio
5
/proc/sys/vm/min_unmapped_ratio
1
/proc/sys/vm/mmap_min_addr
65536
/proc/sys/vm/mmap_rnd_bits
28
/proc/sys/vm/mmap_rnd_compat_bits
8
/proc/sys/vm/nr_hugepages
0
/proc/sys/vm/nr_hugepages_mempolicy
0
/proc/sys/vm/nr_overcommit_hugepages
0
/proc/sys/vm/nr_pdflush_threads
0
/proc/sys/vm/numa_zonelist_order
default
/proc/sys/vm/oom_dump_tasks
1
/proc/sys/vm/oom_kill_allocating_task
0
/proc/sys/vm/overcommit_kbytes
0
/proc/sys/vm/overcommit_memory
2
/proc/sys/vm/overcommit_ratio
80
/proc/sys/vm/page-cluster
3
/proc/sys/vm/panic_on_oom
0
/proc/sys/vm/percpu_pagelist_fraction
0
/proc/sys/vm/stat_interval
1
/proc/sys/vm/stat_refresh
/proc/sys/vm/swappiness
10
/proc/sys/vm/user_reserve_kbytes
31036
/proc/sys/vm/vfs_cache_pressure
100
/proc/sys/vm/watermark_scale_factor
10
/proc/sys/vm/zone_reclaim_mode
0
Thnx.
Ciao,
Gerhard
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next prev parent reply other threads:[~2017-03-17 20:08 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <aa4a3217-f94c-0477-b573-796c84255d1e@wiesinger.com>
[not found] ` <c4ddfc91-7c84-19ed-b69a-18403e7590f9@wiesinger.com>
2016-12-09 7:06 ` Still OOM problems with 4.9er kernels Gerhard Wiesinger
2016-12-09 13:40 ` Michal Hocko
2016-12-09 15:52 ` Gerhard Wiesinger
2016-12-09 15:58 ` Gerhard Wiesinger
2016-12-09 16:09 ` Michal Hocko
2016-12-09 16:58 ` Gerhard Wiesinger
2016-12-09 17:30 ` Michal Hocko
2016-12-09 18:01 ` Gerhard Wiesinger
2016-12-09 21:42 ` Vlastimil Babka
2016-12-10 13:50 ` Gerhard Wiesinger
2016-12-12 8:24 ` Michal Hocko
2016-12-23 2:55 ` Minchan Kim
2017-01-01 17:20 ` Gerhard Wiesinger
2017-01-04 8:40 ` Gerhard Wiesinger
2017-01-04 9:11 ` Michal Hocko
2017-02-26 8:40 ` Still OOM problems with 4.9er/4.10er kernels Gerhard Wiesinger
2017-02-27 8:27 ` Michal Hocko
2017-02-28 6:06 ` Gerhard Wiesinger
2017-02-28 8:14 ` Michal Hocko
2017-02-27 9:02 ` Minchan Kim
2017-02-27 9:44 ` Michal Hocko
2017-02-28 5:17 ` Minchan Kim
2017-02-28 8:12 ` Michal Hocko
2017-03-02 7:17 ` Minchan Kim
2017-03-16 6:38 ` Gerhard Wiesinger
2017-03-16 8:27 ` Michal Hocko
2017-03-16 8:47 ` lkml
2017-03-16 9:08 ` Michal Hocko
2017-03-16 9:23 ` lkml
2017-03-16 9:39 ` Michal Hocko
2017-03-17 16:37 ` Gerhard Wiesinger
2017-03-17 17:13 ` Michal Hocko
2017-03-17 20:08 ` Gerhard Wiesinger [this message]
2017-03-19 8:17 ` Gerhard Wiesinger
2017-03-20 1:54 ` Tetsuo Handa
2017-03-19 15:18 ` Michal Hocko
2017-03-19 16:02 ` Gerhard Wiesinger
2017-03-20 3:05 ` Mike Galbraith
2017-03-21 5:59 ` Gerhard Wiesinger
2017-03-21 7:13 ` Mike Galbraith
2017-03-23 7:16 ` Gerhard Wiesinger
2017-03-23 8:38 ` Mike Galbraith
2017-03-23 14:46 ` Tetsuo Handa
2017-03-26 8:36 ` Gerhard Wiesinger
2016-12-09 16:03 ` Still OOM problems with 4.9er kernels Gerhard Wiesinger
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