From: Chris Down <chris@chrisdown.name>
To: Michal Hocko <mhocko@suse.com>
Cc: zangchunxin@bytedance.com, hannes@cmpxchg.org,
vdavydov.dev@gmail.com, akpm@linux-foundation.org, tj@kernel.org,
lizefan@huawei.com, corbet@lwn.net, ast@kernel.org,
daniel@iogearbox.net, kafai@fb.com, songliubraving@fb.com,
yhs@fb.com, andriin@fb.com, john.fastabend@gmail.com,
kpsingh@chromium.org, cgroups@vger.kernel.org,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH] mm/memcontrol: Add the drop_cache interface for cgroup v2
Date: Mon, 21 Sep 2020 11:42:57 +0100 [thread overview]
Message-ID: <20200921104257.GA632859@chrisdown.name> (raw)
In-Reply-To: <20200921081200.GE12990@dhcp22.suse.cz>
Michal Hocko writes:
>On Mon 21-09-20 16:02:55, zangchunxin@bytedance.com wrote:
>> From: Chunxin Zang <zangchunxin@bytedance.com>
>>
>> In the cgroup v1, we have 'force_mepty' interface. This is very
>> useful for userspace to actively release memory. But the cgroup
>> v2 does not.
>>
>> This patch reuse cgroup v1's function, but have a new name for
>> the interface. Because I think 'drop_cache' may be is easier to
>> understand :)
>
>This should really explain a usecase. Global drop_caches is a terrible
>interface and it has caused many problems in the past. People have
>learned to use it as a remedy to any problem they might see and cause
>other problems without realizing that. This is the reason why we even
>log each attempt to drop caches.
>
>I would rather not repeat the same mistake on the memcg level unless
>there is a very strong reason for it.
I agree with Michal. We already have ways to do best-effort memory release on
cgroup v2, primarily with memory.high. Singling out a category of memory for
reclaim has historically proved to be a fool's errand.
next prev parent reply other threads:[~2020-09-21 10:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 8:02 [PATCH] mm/memcontrol: Add the drop_cache interface for cgroup v2 zangchunxin
2020-09-21 8:12 ` Michal Hocko
2020-09-21 10:42 ` Chris Down [this message]
2020-09-21 10:55 ` Yafang Shao
2020-09-21 11:05 ` Michal Hocko
2020-09-21 11:23 ` Yafang Shao
2020-09-21 11:36 ` Michal Hocko
2020-09-22 4:20 ` Yafang Shao
2020-09-22 7:27 ` Michal Hocko
2020-09-22 8:06 ` Yafang Shao
2020-09-22 10:01 ` Michal Hocko
2020-09-22 9:43 ` [External] " Chunxin Zang
2020-09-22 9:43 ` Chunxin Zang
2020-09-22 9:51 ` Chris Down
2020-09-22 10:24 ` Chunxin Zang
2020-09-22 10:42 ` Chris Down
2020-09-22 12:37 ` Chunxin Zang
2020-09-22 12:43 ` Chris Down
2020-09-23 2:35 ` Chunxin Zang
2020-09-22 19:57 ` Shakeel Butt
2020-09-23 2:40 ` Chunxin Zang
2020-09-21 15:55 ` Shakeel Butt
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