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From: Michal Hocko <mhocko@suse.com>
To: Neil Sun <neilsun@yunify.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/vmscan.c: drop_slab_node with task's memcg
Date: Tue, 6 Apr 2021 13:39:00 +0200	[thread overview]
Message-ID: <YGxIVDXw7wtBytIg@dhcp22.suse.cz> (raw)
In-Reply-To: <4dba277d-e497-5c34-0e68-fd2283585de2@yunify.com>

On Tue 06-04-21 19:30:22, Neil Sun wrote:
> On 2021/4/6 15:21, Michal Hocko wrote:
> > 
> > You are changing semantic of the existing user interface. This knob has
> > never been memcg aware and it is supposed to have a global impact. I do
> > not think we can simply change that without some users being surprised
> > or even breaking them.
> 
> Yes, do you think add new interface to sysfs is a good way? such as
> /sys/fs/cgroup/memory/lxc/i-vbe1u8o7/memory.kmem.drop_caches

There were other attempts to add a memcg specific alternative to
drop_caches. A lack of a strong usecase has been a reason that no such
attempt has been merged until now. drop_caches is a problematic
interface because it is really coarse and people have learned to (ab)use
it to workaround problem rather than fix them properly.

What is your usecase?
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2021-04-06 11:39 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-02 10:38 [PATCH] mm/vmscan.c: drop_slab_node with task's memcg Neil Sun
2021-04-02 14:38 ` kernel test robot
2021-04-02 14:38   ` kernel test robot
2021-04-02 14:50 ` kernel test robot
2021-04-02 14:50   ` kernel test robot
2021-04-06  7:21 ` Michal Hocko
2021-04-06 11:30   ` Neil Sun
2021-04-06 11:39     ` Michal Hocko [this message]
2021-04-06 14:34       ` Neil Sun
2021-04-06 14:39         ` Michal Hocko
2021-04-06 15:12           ` Neil Sun
2021-04-06 17:38             ` Michal Hocko

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