From: Michal Hocko <mhocko@kernel.org>
To: Fam Zheng <zhengfeiran@bytedance.com>
Cc: cgroups@vger.kernel.org, "Linux MM" <linux-mm@kvack.org>,
tj@kernel.org, "Johannes Weiner" <hannes@cmpxchg.org>,
lizefan@huawei.com, "Vladimir Davydov" <vdavydov.dev@gmail.com>,
duanxiongchun@bytedance.com, 张永肃 <zhangyongsu@bytedance.com>
Subject: Re: memory cgroup pagecache and inode problem
Date: Fri, 4 Jan 2019 11:12:16 +0100 [thread overview]
Message-ID: <20190104101216.GM31793@dhcp22.suse.cz> (raw)
In-Reply-To: <E699E11E-32B9-4061-93BD-54FE52F972BA@bytedance.com>
On Fri 04-01-19 18:02:19, Fam Zheng wrote:
>
>
> > On Jan 4, 2019, at 17:04, Michal Hocko <mhocko@kernel.org> wrote:
> >
> > This is a natural side effect of shared memory, I am afraid. Isolated
> > memory cgroups should limit any shared resources to bare minimum. You
> > will get "who touches first gets charged" behavior otherwise and that is
> > not really deterministic.
>
> I don’t quite understand your comment. I think the current behavior
> for the ext4_inode_cachep slab family is just “who touches first
> gets charged”, and later users of the same file from a different mem
> cgroup can benefit from the cache, keep it from being released, but
> doesn’t get charged.
Yes, this is exactly what I've said. And that leads to non-deterministic
behavior because users from other memcgs are keeping charges alive and
the isolation really doesn't work properly. Think of it as using memory
on behalf of other party that is supposed to be isolated from you.
Sure this can work reasonably well if the sharing is not really
predominated.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-01-04 10:12 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <15614FDC-198E-449B-BFAF-B00D6EF61155@bytedance.com>
2019-01-04 4:44 ` memory cgroup pagecache and inode problem Fam Zheng
2019-01-04 5:00 ` Yang Shi
2019-01-04 5:12 ` Fam Zheng
2019-01-04 19:36 ` Yang Shi
2019-01-07 5:10 ` Fam Zheng
2019-01-07 8:53 ` Michal Hocko
2019-01-07 9:01 ` Fam Zheng
2019-01-07 9:13 ` Michal Hocko
2019-01-09 4:33 ` Fam Zheng
2019-01-10 5:36 ` Yang Shi
2019-01-10 8:30 ` Fam Zheng
2019-01-10 8:41 ` Michal Hocko
2019-01-16 0:50 ` Yang Shi
2019-01-16 3:52 ` Fam Zheng
2019-01-16 7:06 ` Michal Hocko
2019-01-16 21:08 ` Yang Shi
2019-01-16 21:06 ` Yang Shi
2019-01-17 2:41 ` Fam Zheng
2019-01-17 5:06 ` Yang Shi
2019-01-19 3:17 ` 段熊春
2019-01-20 23:15 ` Shakeel Butt
2019-01-20 23:15 ` Shakeel Butt
2019-01-20 23:20 ` Shakeel Butt
2019-01-21 10:27 ` Michal Hocko
2019-01-04 9:04 ` Michal Hocko
2019-01-04 10:02 ` Fam Zheng
2019-01-04 10:12 ` Michal Hocko [this message]
2019-01-04 10:35 ` Fam Zheng
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