From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Shakeel Butt <shakeelb@google.com>,
Cgroups <cgroups@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH v5 2/2] mm/memcontrol.c: Reduce reclaim retries in mem_cgroup_resize_limit()
Date: Thu, 22 Feb 2018 18:38:11 +0300 [thread overview]
Message-ID: <0927bcab-7e2c-c6f9-d16a-315ac436ba98@virtuozzo.com> (raw)
In-Reply-To: <20180222153343.GN30681@dhcp22.suse.cz>
On 02/22/2018 06:33 PM, Michal Hocko wrote:
> On Thu 22-02-18 18:13:11, Andrey Ryabinin wrote:
>>
>>
>> On 02/22/2018 05:09 PM, Michal Hocko wrote:
>>> On Thu 22-02-18 16:50:33, Andrey Ryabinin wrote:
>>>> On 02/21/2018 11:17 PM, Andrew Morton wrote:
>>>>> On Fri, 19 Jan 2018 16:11:18 +0100 Michal Hocko <mhocko@kernel.org> wrote:
>>>>>
>>>>>> And to be honest, I do not really see why keeping retrying from
>>>>>> mem_cgroup_resize_limit should be so much faster than keep retrying from
>>>>>> the direct reclaim path. We are doing SWAP_CLUSTER_MAX batches anyway.
>>>>>> mem_cgroup_resize_limit loop adds _some_ overhead but I am not really
>>>>>> sure why it should be that large.
>>>>>
>>>>> Maybe restarting the scan lots of times results in rescanning lots of
>>>>> ineligible pages at the start of the list before doing useful work?
>>>>>
>>>>> Andrey, are you able to determine where all that CPU time is being spent?
>>>>>
>>>>
>>>> I should have been more specific about the test I did. The full script looks like this:
>>>>
>>>> mkdir -p /sys/fs/cgroup/memory/test
>>>> echo $$ > /sys/fs/cgroup/memory/test/tasks
>>>> cat 4G_file > /dev/null
>>>> while true; do cat 4G_file > /dev/null; done &
>>>> loop_pid=$!
>>>> perf stat echo 50M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
>>>> echo -1 > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
>>>> kill $loop_pid
>>>>
>>>>
>>>> I think the additional loops add some overhead and it's not that big by itself, but
>>>> this small overhead allows task to refill slightly more pages, increasing
>>>> the total amount of pages that mem_cgroup_resize_limit() need to reclaim.
>>>>
>>>> By using the following commands to show the the amount of reclaimed pages:
>>>> perf record -e vmscan:mm_vmscan_memcg_reclaim_end echo 50M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
>>>> perf script|cut -d '=' -f 2| paste -sd+ |bc
>>>>
>>>> I've got 1259841 pages (4.9G) with the patch vs 1394312 pages (5.4G) without it.
>>>
>>> So how does the picture changes if you have multiple producers?
>>>
>>
>> Drastically, in favor of the patch. But numbers *very* fickle from run to run.
>>
>> Inside 5G vm with 4 cpus (qemu -m 5G -smp 4) and 4 processes in cgroup reading 1G files:
>> "while true; do cat /1g_f$i > /dev/null; done &"
>>
>> with the patch:
>> best: 1.04 secs, 9.7G reclaimed
>> worst: 2.2 secs, 16G reclaimed.
>>
>> without:
>> best: 5.4 sec, 35G reclaimed
>> worst: 22.2 sec, 136G reclaimed
>
> Could you also compare how much memory do we reclaim with/without the
> patch?
>
I did and I wrote the results. Please look again.
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next prev parent reply other threads:[~2018-02-22 15:37 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-20 10:24 [PATCH 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Andrey Ryabinin
2017-12-20 10:24 ` [PATCH 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2017-12-20 10:33 ` [PATCH 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2017-12-20 11:32 ` Andrey Ryabinin
2017-12-20 11:34 ` Michal Hocko
2017-12-20 18:15 ` Shakeel Butt
2017-12-21 10:00 ` Andrey Ryabinin
2017-12-20 13:21 ` [PATCH v2 " Andrey Ryabinin
2017-12-20 13:21 ` [PATCH v2 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2017-12-20 13:53 ` [PATCH v2 1/2] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2018-01-09 16:58 ` [PATCH v3 " Andrey Ryabinin
2018-01-09 16:58 ` [PATCH v3 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions Andrey Ryabinin
2018-01-09 17:10 ` Shakeel Butt
2018-01-09 17:26 ` Andrey Ryabinin
2018-01-09 23:26 ` Andrew Morton
2018-01-10 12:43 ` [PATCH v4] mm/memcg: try harder to decrease [memory,memsw].limit_in_bytes Andrey Ryabinin
2018-01-10 22:31 ` Andrew Morton
2018-01-11 11:59 ` Andrey Ryabinin
2018-01-12 0:21 ` Andrew Morton
2018-01-12 9:08 ` Andrey Ryabinin
2018-01-11 10:42 ` Michal Hocko
2018-01-11 12:21 ` Andrey Ryabinin
2018-01-11 12:46 ` Michal Hocko
2018-01-11 15:23 ` Andrey Ryabinin
2018-01-11 16:29 ` Michal Hocko
2018-01-11 21:59 ` Andrey Ryabinin
2018-01-12 12:24 ` Michal Hocko
2018-01-12 22:57 ` Shakeel Butt
2018-01-15 12:29 ` Andrey Ryabinin
2018-01-15 17:04 ` Shakeel Butt
2018-01-15 12:30 ` Andrey Ryabinin
2018-01-15 12:46 ` Michal Hocko
2018-01-15 12:53 ` Andrey Ryabinin
2018-01-15 12:58 ` Michal Hocko
2018-01-09 17:08 ` [PATCH v3 1/2] " Andrey Ryabinin
2018-01-09 17:22 ` Shakeel Butt
2018-01-19 13:25 ` [PATCH v5 1/2] mm/memcontrol.c: " Andrey Ryabinin
2018-01-19 13:25 ` [PATCH v5 2/2] mm/memcontrol.c: Reduce reclaim retries in mem_cgroup_resize_limit() Andrey Ryabinin
2018-01-19 13:35 ` Michal Hocko
2018-01-19 14:49 ` Shakeel Butt
2018-01-19 15:11 ` Michal Hocko
2018-01-19 15:24 ` Shakeel Butt
2018-01-19 15:31 ` Michal Hocko
2018-02-21 20:17 ` Andrew Morton
2018-02-22 13:50 ` Andrey Ryabinin
2018-02-22 14:09 ` Michal Hocko
2018-02-22 15:13 ` Andrey Ryabinin
2018-02-22 15:33 ` Michal Hocko
2018-02-22 15:38 ` Andrey Ryabinin [this message]
2018-02-22 15:44 ` Michal Hocko
2018-02-22 16:01 ` Andrey Ryabinin
2018-02-22 16:30 ` Michal Hocko
2018-01-19 13:32 ` [PATCH v5 1/2] mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes Michal Hocko
2018-01-25 19:44 ` Andrey Ryabinin
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