[Intel-gfx] [PATCH] drm/i915: Handle ENOSPC after failing to insert a mappable node

[Chris Wilson]

On Tue, Jul 19, 2016 at 08:55:55AM +0200, Daniel Vetter wrote:
> On Sat, Jul 16, 2016 at 06:42:36PM +0100, Chris Wilson wrote:
> > Even after adding individual page support for GTT mmaping, we can still
> > fail to find any space within the mappable region, and
> > drm_mm_insert_node() will then report ENOSPC. We have to then handle
> > this error by using the shmem access to the pages.
> > 
> > Fixes: b50a53715f09 ("drm/i915: Support for pread/pwrite ... objects")
> > Testcase: igt/gem_concurrent_blit
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Ankitprasad Sharma <ankitprasad.r.sharma at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com
> 
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Thanks for the review, pushed.

Ideas for how we can stress this a bit directly than
gem_concurrent_blit?

We need to have many threads all pinning and then hitting the slow path
in the read (thus allowing another thread to come in and fail to claim
some aperture space for itself). Tricksy.

Hmm, how about fault-injection under I915_DEBUG?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre