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

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Message-ID: <20200818101756.GA155582@chrisdown.name>
Date:   Tue, 18 Aug 2020 11:17:56 +0100
From:   Chris Down <chris@...isdown.name>
To:     peterz@...radead.org
Cc:     Michal Hocko <mhocko@...e.com>, Waiman Long <longman@...hat.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

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".