linux-kernel - Re: Re: [RFC PATCH net-next 0/3] sock: Be aware of memcg pressure on alloc

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Date:   Fri, 15 Sep 2023 16:47:22 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Yosry Ahmed <yosryahmed@...gle.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Yu Zhao <yuzhao@...gle.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Yafang Shao <laoar.shao@...il.com>,
        Kuniyuki Iwashima <kuniyu@...zon.com>,
        Martin KaFai Lau <martin.lau@...nel.org>,
        Breno Leitao <leitao@...ian.org>,
        Alexander Mikhalitsyn <alexander@...alicyn.com>,
        David Howells <dhowells@...hat.com>,
        Jason Xing <kernelxing@...cent.com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: Re: [RFC PATCH net-next 0/3] sock: Be aware of memcg pressure on
 alloc

On 9/15/23 5:20 AM, Shakeel Butt wrote:
> On Fri, Sep 01, 2023 at 02:21:25PM +0800, Abel Wu wrote:
>>
> [...]
>> As expected, no obvious performance gain or loss observed. As for the
>> issue we encountered, this patchset provides better worst-case behavior
>> that such OOM cases are reduced at some extent. While further fine-
>> grained traffic control is what the workloads need to think about.
>>
> 
> I agree with the motivation but I don't agree with the solution (patch 2
> and 3). This is adding one more heuristic in the code which you yourself
> described as helped to some extent. In addition adding more dependency
> on vmpressure subsystem which is in weird state. Vmpressure is a cgroup
> v1 feature which somehow networking subsystem is relying on for cgroup
> v2 deployments. In addition vmpressure acts differently for workloads
> with different memory types (mapped, mlocked, kernel memory).

Indeed.

> 
> Anyways, have you explored the BPF based approach. You can induce socket
> pressure at the points you care about and define memory pressure however
> your use-case cares for. You can define memory pressure using PSI or
> vmpressure or maybe with MEMCG_HIGH events. What do you think?

Yeah, this sounds much better. I will re-implement this patchset based
on your suggestion. Thank you for helpful comments!

Best,
	Abel