[Bug 78023] [PNV/HSW/BDW bisected]igt/gem_exec_lut_handle is slow

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=78023

--- Comment #5 from Chris Wilson <chris at chris-wilson.co.uk> ---
The root cause is ppgtt:

commit 1f70999f9052f5a1b0ce1a55aff3808f2ec9fe42
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Mon Jan 27 22:43:07 2014 +0000

    drm/i915: Prevent recursion by retiring requests when the ring is full

    As the VM do not track activity of objects and instead use a large
    hammer to forcibly idle and evict all of their associated objects when
    one is released, it is possible for that to cause a recursion when we
    need to wait for free space on a ring and call retire requests.
    (intel_ring_begin -> intel_ring_wait_request ->
    i915_gem_retire_requests_ring -> i915_gem_context_free ->
    i915_gem_evict_vm -> i915_gpu_idle -> intel_ring_begin etc)

    In order to remove the requirement for calling retire-requests from
    intel_ring_wait_request, we have to inline a couple of steps from
    retiring requests, notably we have to record the position of the request
    we wait for and use that to update the available ring space.

    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
    Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

removes the i915_gem_retire_requests_ring() when we run out of ring space, and
this test has no explicit request retiring and so depends upon this implicit
retire.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20140505/5d449bed/attachment.html>