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Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory
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To:     Chris Down <chris@chrisdown.name>, peterz@infradead.org
Cc:     Michal Hocko <mhocko@suse.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Ingo Molnar <mingo@kernel.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org
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From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <989570d6-639e-6385-d638-c4729665c2e4@redhat.com>
Date:   Sat, 22 Aug 2020 22:49:19 -0400
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On 8/18/20 6:17 AM, Chris Down wrote:
> peterz@infradead.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