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From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Michal Hocko <mhocko@suse.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] Support hugetlb charge moving at task migration
Date: Thu, 7 Oct 2021 23:39:15 +0800	[thread overview]
Message-ID: <e52a85c4-e4b4-b91a-b5b4-4da6c44c5959@linux.alibaba.com> (raw)
In-Reply-To: <YVWVk559nm2xZ98R@dhcp22.suse.cz>

Hi Michal,

(Sorry for late reply due to my holidays)
On 2021/9/30 18:46, Michal Hocko wrote:
> On Wed 29-09-21 18:19:26, Baolin Wang wrote:
>> Hi,
>>
>> Now in the hugetlb cgroup, charges associated with a task aren't moved
>> to the new hugetlb cgroup at task migration, which is odd for hugetlb
>> cgroup usage.
> 
> Could you elaborate some more about the usecase and/or problems you see
> with the existing semantic?

The problems is that, it did not check if the tasks can move to the new 
hugetlb cgroup if the new hugetlb cgroup has a limitation, and the 
hugetlb cgroup usage is incorrect when moving tasks among hugetlb cgroups.

> 
>> This patch set adds hugetlb cgroup charge moving when
>> migrate tasks among cgroups, which are based on the memcg charge moving.
> 
> Memcg charge moving has shown some problems over time and hence this is
> not part of cgroup v2 interface anymore. Even for cgroup v1 this has

Sorry, I missed this part, could you elaborate on the issues? I can have 
a close look about the problems of memcg charge moving.

> been an opt-in. I do not see anything like that in this patch series.
> Why should all existing workloads follow a different semantic during
> task migration now?

But I think it is reasonable for some cases moving the old charging to 
the new cgroup when task migration. Maybe I can add a new hugetlb cgroup 
file to control if need this or not?

Thanks for your comments.


  reply	other threads:[~2021-10-07 15:38 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 10:19 Baolin Wang
2021-09-29 10:19 ` [PATCH 1/2] hugetlb_cgroup: Add interfaces to move hugetlb charge " Baolin Wang
2021-09-29 10:19 ` [PATCH 2/2] hugetlb_cgroup: Add post_attach interface for tasks migration Baolin Wang
2021-09-30 10:46 ` [PATCH 0/2] Support hugetlb charge moving at task migration Michal Hocko
2021-10-07 15:39   ` Baolin Wang [this message]
2021-10-08  7:12     ` Michal Hocko
2021-10-08  9:17       ` Baolin Wang
2021-10-08 11:55         ` Michal Hocko
2021-10-09 14:24           ` Baolin Wang

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