From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>,
"Li,Rongqing" <lirongqing@baidu.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>
Subject: Re: 答复: 答复: [PATCH] mm/memcontrol.c: speed up to force empty a memory cgroup
Date: Wed, 21 Mar 2018 01:35:05 +0300 [thread overview]
Message-ID: <e265c518-968b-8669-ad22-671c781ad96e@virtuozzo.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1803201514340.14003@chino.kir.corp.google.com>
On 03/21/2018 01:15 AM, David Rientjes wrote:
> On Wed, 21 Mar 2018, Andrey Ryabinin wrote:
>
>>>>> It would probably be best to limit the
>>>>> nr_pages to the amount that needs to be reclaimed, though, rather than
>>>>> over reclaiming.
>>>>
>>>> How do you achieve that? The charging path is not synchornized with the
>>>> shrinking one at all.
>>>>
>>>
>>> The point is to get a better guess at how many pages, up to
>>> SWAP_CLUSTER_MAX, that need to be reclaimed instead of 1.
>>>
>>>>> If you wanted to be invasive, you could change page_counter_limit() to
>>>>> return the count - limit, fix up the callers that look for -EBUSY, and
>>>>> then use max(val, SWAP_CLUSTER_MAX) as your nr_pages.
>>>>
>>>> I am not sure I understand
>>>>
>>>
>>> Have page_counter_limit() return the number of pages over limit, i.e.
>>> count - limit, since it compares the two anyway. Fix up existing callers
>>> and then clamp that value to SWAP_CLUSTER_MAX in
>>> mem_cgroup_resize_limit(). It's a more accurate guess than either 1 or
>>> 1024.
>>>
>>
>> JFYI, it's never 1, it's always SWAP_CLUSTER_MAX.
>> See try_to_free_mem_cgroup_pages():
>> ....
>> struct scan_control sc = {
>> .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
>>
>
> Is SWAP_CLUSTER_MAX the best answer if I'm lowering the limit by 1GB?
>
Absolutely not. I completely on your side here.
I've tried to fix this recently - http://lkml.kernel.org/r/20180119132544.19569-2-aryabinin@virtuozzo.com
I guess that Andrew decided to not take my patch, because Michal wasn't
happy about it (see mail archives if you want more details).
next prev parent reply other threads:[~2018-03-20 22:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-19 8:29 [PATCH] mm/memcontrol.c: speed up to force empty a memory cgroup Li RongQing
2018-03-19 8:53 ` Michal Hocko
[not found] ` <2AD939572F25A448A3AE3CAEA61328C23745764B@BC-MAIL-M28.internal.baidu.com>
2018-03-19 10:37 ` 答复: " Michal Hocko
2018-03-19 10:51 ` 答复: " Li,Rongqing
2018-03-19 17:51 ` David Rientjes
2018-03-20 8:39 ` Michal Hocko
2018-03-20 20:29 ` David Rientjes
2018-03-20 22:08 ` Andrey Ryabinin
2018-03-20 22:15 ` David Rientjes
2018-03-20 22:35 ` Andrey Ryabinin [this message]
2018-03-20 22:45 ` David Rientjes
2018-03-21 9:59 ` Michal Hocko
2018-03-23 2:58 ` Li,Rongqing
2018-03-23 10:08 ` Michal Hocko
2018-03-23 12:04 ` 答复: " Li,Rongqing
2018-03-23 12:29 ` Michal Hocko
2018-03-23 10:34 ` Michal Hocko
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