RE: [RFC PATCH v3 0/4] Deliver vGPU display vblank event to userspace

[Zhang, Tina]

> -----Original Message-----
> From: Gerd Hoffmann [mailto:kraxel@xxxxxxxxxx]
> Sent: Thursday, June 27, 2019 2:23 PM
> To: Zhang, Tina <tina.zhang@xxxxxxxxx>
> Cc: intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; Lv, Zhiyuan
> <zhiyuan.lv@xxxxxxxxx>; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; Tian, Kevin
> <kevin.tian@xxxxxxxxx>; Yuan, Hang <hang.yuan@xxxxxxxxx>;
> alex.williamson@xxxxxxxxxx
> Subject: Re: [RFC PATCH v3 0/4] Deliver vGPU display vblank event to
> userspace
> 
>   Hi,
> 
> > Instead of delivering page flip events, we choose to post display
> > vblank event. Handling page flip events for both primary plane and
> > cursor plane may make user space quite busy, although we have the
> > mask/unmask mechansim for mitigation. Besides, there are some cases
> > that guest app only uses one framebuffer for both drawing and display.
> > In such case, guest OS won't do the plane page flip when the
> > framebuffer is updated, thus the user land won't be notified about the
> updated framebuffer.
> 
> What happens when the guest is idle and doesn't draw anything to the
> framebuffer?
The vblank event will be delivered to userspace as well, unless guest OS disable the pipe.
Does it make sense to vfio/display?
Thanks.

BR,
Tina
> 
> cheers,
>   Gerd