From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: ultrachin@163.com, akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, brookxu.cn@gmail.com,
chen xiaoguang <xiaoggchen@tencent.com>,
zeng jingxiang <linuszeng@tencent.com>,
lu yihui <yihuilu@tencent.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH] mm: Free per cpu pages async to shorten program exit time
Date: Mon, 11 Oct 2021 11:40:12 +0200 [thread overview]
Message-ID: <278a6cda-3095-5e27-e136-2765f73bc67d@redhat.com> (raw)
In-Reply-To: <YWQDqtnA5FXk7xan@dhcp22.suse.cz>
On 11.10.21 11:28, Michal Hocko wrote:
> On Fri 08-10-21 10:17:50, David Hildenbrand wrote:
>> On 08.10.21 08:39, ultrachin@163.com wrote:
>>> From: chen xiaoguang <xiaoggchen@tencent.com>
>>>
>>> The exit time is long when program allocated big memory and
>>> the most time consuming part is free memory which takes 99.9%
>>> of the total exit time. By using async free we can save 25% of
>>> exit time.
>>>
>>> Signed-off-by: chen xiaoguang <xiaoggchen@tencent.com>
>>> Signed-off-by: zeng jingxiang <linuszeng@tencent.com>
>>> Signed-off-by: lu yihui <yihuilu@tencent.com>
>>
>> I recently discussed with Claudio if it would be possible to tear down the
>> process MM deferred, because for some use cases (secure/encrypted
>> virtualization, very large mmaps) tearing down the page tables is already
>> the much more expensive operation.
>>
>> There is mmdrop_async(), and I wondered if one could reuse that concept when
>> tearing down a process -- I didn't look into feasibility, however, so it's
>> just some very rough idea.
>
> This is not a new problem. Large process tear down can take ages. The
> primary road block has been accounting. This lot of work has to be
> accounted to the proper domain (e.g. cpu cgroup).
In general, yes. For some setups where admins don't care about that
accounting (e.g., enabled via some magic toggle for large VMs), I guess
this accounting isn't the major roadblock, correct?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-10-11 9:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-08 6:39 [PATCH] mm: Free per cpu pages async to shorten program exit time ultrachin
2021-10-08 8:17 ` David Hildenbrand
2021-10-08 8:52 ` Claudio Imbrenda
2021-10-08 9:15 ` David Hildenbrand
2021-10-08 9:22 ` Claudio Imbrenda
2021-10-08 9:24 ` David Hildenbrand
2021-10-08 12:38 ` Vlastimil Babka
2021-10-08 12:54 ` Claudio Imbrenda
2021-10-08 12:55 ` David Hildenbrand
2021-10-10 22:42 ` Andrew Morton
2021-10-11 9:28 ` Michal Hocko
2021-10-11 9:40 ` David Hildenbrand [this message]
2021-10-11 11:23 ` Michal Hocko
2021-10-13 17:38 ` Daniel Jordan
2021-10-08 11:27 ` kernel test robot
2021-10-08 12:29 ` kernel test robot
2021-10-11 8:20 ` [mm] 3e55b36596: kernel_BUG_at_mm/page_alloc.c kernel test robot
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