Re: [RFC PATCH v3 00/11] new cgroup controller for gpu/drm subsystem

Kenny Ho
2019-06-30T05:10:28Z

On Thu, Jun 27, 2019 at 3:24 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> Another question I have: What about HMM? With the device memory zone
> the core mm will be a lot more involved in managing that, but I also
> expect that we'll have classic buffer-based management for a long time
> still. So these need to work together, and I fear slightly that we'll
> have memcg and drmcg fighting over the same pieces a bit perhaps?
>
> Adding Jerome, maybe he has some thoughts on this.

I just did a bit of digging and this looks like the current behaviour:
https://www.kernel.org/doc/html/v5.1/vm/hmm.html#memory-cgroup-memcg-and-rss-accounting

"For now device memory is accounted as any regular page in rss
counters (either anonymous if device page is used for anonymous, file
if device page is used for file backed page or shmem if device page is
used for shared memory). This is a deliberate choice to keep existing
applications, that might start using device memory without knowing
about it, running unimpacted.

A drawback is that the OOM killer might kill an application using a
lot of device memory and not a lot of regular system memory and thus
not freeing much system memory. We want to gather more real world
experience on how applications and system react under memory pressure
in the presence of device memory before deciding to account device
memory differently."

Regards,
Kenny
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