Re: [PATCH] drm/virtio: delay pinning the pages till first use

On Tue, Nov 2, 2021 at 6:07 AM Gerd Hoffmann kraxel@redhat.com wrote:

On Tue, Nov 02, 2021 at 12:31:39PM +0100, Maksym Wezdecki wrote:

...

From: mwezdeck maksym.wezdecki@collabora.co.uk

The idea behind the commit:

1. not pin the pages during resource_create ioctl
2. pin the pages on the first use during:
   • transfer_*_host ioctl
     • map ioctl

i.e. basically lazy pinning. Approach looks sane to me.

...

3. introduce new ioctl for pinning pages on demand

What is the use case for this ioctl? In any case this should be a separate patch.

Lazy pinning can be a nice optimization that userspace does not necessarily need to know about. This patch however skips pinning for execbuffer ioctl and introduces a new pin ioctl instead. That is a red flag.