linux-kernel - Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control

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Date:   Sat, 22 Aug 2020 22:49:19 -0400
From:   Waiman Long <longman@...hat.com>
To:     Chris Down <chris@...isdown.name>, peterz@...radead.org
Cc:     Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory
 control

On 8/18/20 6:17 AM, Chris Down wrote:
> peterz@...radead.org writes:
>> But then how can it run-away like Waiman suggested?
>
> Probably because he's not running with that commit at all. We and 
> others use this to prevent runaway allocation on a huge range of 
> production and desktop use cases and it works just fine.
>
>> /me goes look... and finds MEMCG_MAX_HIGH_DELAY_JIFFIES.
>>
>> That's a fail... :-(
>
> I'd ask that you understand a bit more about the tradeoffs and 
> intentions of the patch before rushing in to declare its failure, 
> considering it works just fine :-)
>
> Clamping the maximal time allows the application to take some action 
> to remediate the situation, while still being slowed down 
> significantly. 2 seconds per allocation batch is still absolutely 
> plenty for any use case I've come across. If you have evidence it 
> isn't, then present that instead of vague notions of "wrongness".
>
Sorry for the late reply.

I ran some test on the latest kernel and and it seems to work as 
expected. I was running the test on an older kernel that doesn't have 
this patch and I was not aware of it before hand.

Sorry for the confusion.

Cheers,
Longman