[Intel-gfx] [PATCH 13/66] drm/i915/gem: Don't drop the timeline lock during execbuf

[Thomas Hellström (Intel)]

On 7/15/20 1:50 PM, Chris Wilson wrote:
> Our timeline lock is our defence against a concurrent execbuf
> interrupting our request construction. we need hold it throughout or,
> for example, a second thread may interject a relocation request in
> between our own relocation request and execution in the ring.
>
> A second, major benefit, is that it allows us to preserve a large chunk
> of the ringbuffer for our exclusive use; which should virtually
> eliminate the threat of hitting a wait_for_space during request
> construction -- although we should have already dropped other
> contentious locks at that point.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>
Reviewed-by: Thomas Hellström <thomas.hellstrom at intel.com>