Re: [PATCH v6 00/10] Support virtio-gpu DRM native context

["Alex Bennée" <alex.bennee@linaro.org>]

Dmitry Osipenko <dmitry.osipenko@collabora.com> writes:

> On 2/17/25 18:22, Alex Bennée wrote:
> ...
>>> This VK_KHR_display problem is only reproducible with your rootfs that
>>> you shared with me. It could be a trouble with your build configs or a
>>> buggy package version used by your rootfs build, more likely the
>>> former.
>> So you have built that latest vkmark? This is a recent addition to
>> vkmark for the 2025.1 release.
>
> Yes, latest 2025.1 from git/master.
>
>> Does vulkaninfo --summary show the extension available for you? It is
>> certainly available on the host side:
>> 
>> VK_KHR_display                         : extension revision 23
>> 
>
> Have it on guest with my rootfs, not with yours. I'd suspect problem is
> with the your Mesa build flags, maybe you haven't enabled necessary
> flags related to WSI.

I can't see any reference in the buildroot recipes. What is your mesa's
build flags?

>
> ..
>>>> With drm_native I get a lot of stutter while running and barely 100FPS
>>>> (compared to ~8000 on pure venus). IMHO we need to figure out why there
>>>> is such a discrepancy before merging because currently it makes more
>>>> sense to use 
>>> If you'd run with Xorg/Wayland directly without a DE, then it should
>>> work okay. This should be a problem with unmapping performance that I'm
>>> thinking about.
>>>
>>> That unmapping problem is partially understood. Unmapping code works
>>> correctly, but we'll need to optimize the flatview code to perform
>>> unmapping immediately.
>> Why immediately? Surely if we are unmapping we can defer it. Or is this
>> a case of having stale mappings making the life of new allocations
>> harder?
>
> Unmapping currently works synchronously for virtio-gpu in QEMU, hence
> deferring it blocks whole virtio-gpu up to 100+ ms. And if multiple
> unmappings are done in a row, then it's 100ms multiplied by the number
> of unmappings.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro