Created attachment 115467 [details]
dmesg

System Environment:
--------------------------
Regression: yes

Platform: BSW
kernel: drm-inte-next-queued: de4de566f84b87f4d5f8265b11932088adb19896(2015-04-29)

Bisect result 
0875546c5318c85c13d07014af5350e9000bc9e9 is the first bad commit
commit 0875546c5318c85c13d07014af5350e9000bc9e9
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Mon Apr 20 09:04:05 2015 -0700

    drm/i915: Fix up the vma aliasing ppgtt binding

    Currently we have the problem that the decision whether ptes need to
    be (re)written is splattered all over the codebase. Move all that into
    i915_vma_bind. This needs a few changes:
    - Just reuse the PIN_* flags for i915_vma_bind and do the conversion
      to vma->bound in there to avoid duplicating the conversion code all
      over.
    - We need to make binding for EXECBUF (i.e. pick aliasing ppgtt if
      around) explicit, add PIN_USER for that.
    - Two callers want to update ptes, give them a PIN_UPDATE for that.

    Of course we still want to avoid double-binding, but that should be
    taken care of:
    - A ppgtt vma will only ever see PIN_USER, so no issue with
      double-binding.
    - A ggtt vma with aliasing ppgtt needs both types of binding, and we
      track that properly now.
    - A ggtt vma without aliasing ppgtt could be bound twice. In the
      lower-level ->bind_vma functions hence unconditionally set
      GLOBAL_BIND when writing the ggtt ptes.

    There's still a bit room for cleanup, but that's for follow-up
    patches.

    v2: Fixup fumbles.

    v3: s/PIN_EXECBUF/PIN_USER/ for clearer meaning, suggested by Chris.

    Cc: Chris Wilson <chris@chris-wilson.co.uk>
    Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
    Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

:040000 040000 5d52d149dfbafae0fbc4869992352b596c4c6af5 37c3febcf1c8cd1da506717e6a6801ebdc625f64 M    driversBug 

detailed description:
-----------------------------

GpuTest triangle-windows performance decreased by about 10%-15%

Reproduce steps:
---------------------------

run GpuTest triangle-windows case and check the performance difference.