Re: [PATCH v1 0/5] Add memory shrinker to VirtIO-GPU DRM driver

[Dmitry Osipenko]

On 3/10/22 01:43, Dmitry Osipenko wrote:
>> I think that, given virgl uses host storage, guest shrinker should be
>> still useful.. so I think continue with this series.
> Guest shrinker indeed will be useful for virgl today. I was already
> questioning why virgl needs both host and guest storages, maybe it will
> move to a host-only storage approach in the future.
> 
> I think the variant with the timer expiration actually could be
> interesting to try because it should allow host to purge its VM BOs by
> itself, preventing host OOMs.

While I was working on shrinker v2, I noticed that host-side allocation
may take a significant time. So I decided to defer implementation of my
idea of using timer-based expiration for host-only BOs. I'll need to
examine it more.

>> For host shrinker, I'll have to look more at when crosvm triggers
>> balloon inflation.  I could still go the MADV:WILLNEED_REPLACE
>> approach instead, which does have the advantage of host kernel not
>> relying on host userspace or vm having a chance to run in order to
>> release pages.  The downside (perhaps?) is it would be more specific
>> to virtgpu-native-context and less so to virgl or venus (but I guess
>> there doesn't currently exist a way for madvise to be useful for vk
>> drivers).
> I'll also take a look at what CrOS does, maybe it has some interesting
> ideas.

I looked at CrOS kernel and crosvm, and haven't noticed anything special
there in regards to purging GPU's memory of VM on host-side memory
pressure. If you'll find something, then please let me know.

I sent out v2 of the shrinker series, but missed to CC you on it by
accident, please find it here [1].

[1]
https://lore.kernel.org/dri-devel/20220314224253.236359-1-dmitry.osipenko@xxxxxxxxxxxxx/T/#t