linux-kernel - Re: [RFC] Per file OOM badness

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Date:   Tue, 30 Jan 2018 10:29:10 +0100
From:   Michel Dänzer <michel@...nzer.net>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Christian.Koenig@....com, linux-mm@...ck.org,
        amd-gfx@...ts.freedesktop.org, Roman Gushchin <guro@...com>
Subject: Re: [RFC] Per file OOM badness

On 2018-01-24 12:50 PM, Michal Hocko wrote:
> On Wed 24-01-18 12:23:10, Michel Dänzer wrote:
>> On 2018-01-24 12:01 PM, Michal Hocko wrote:
>>> On Wed 24-01-18 11:27:15, Michel Dänzer wrote:
> [...]
>>>> 2. If the OOM killer kills a process which is sharing BOs with another
>>>> process, this should result in the other process dropping its references
>>>> to the BOs as well, at which point the memory is released.
>>>
>>> OK. How exactly are those BOs mapped to the userspace?
>>
>> I'm not sure what you're asking. Userspace mostly uses a GEM handle to
>> refer to a BO. There can also be userspace CPU mappings of the BO's
>> memory, but userspace doesn't need CPU mappings for all BOs and only
>> creates them as needed.
> 
> OK, I guess you have to bear with me some more. This whole stack is a
> complete uknonwn. I am mostly after finding a boundary where you can
> charge the allocated memory to the process so that the oom killer can
> consider it. Is there anything like that? Except for the proposed file
> handle hack?

How about the other way around: what APIs can we use to charge /
"uncharge" memory to a process? If we have those, we can experiment with
different places to call them.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer