[Intel-gfx] [PATCH 4/4] drm/i915: Opportunistically reduce flushing at execbuf

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                                  364/364              364/364
ILK              +3                 362/366              365/366
SNB                                  448/450              448/450
IVB                                  497/498              497/498
BYT                                  289/289              289/289
HSW                                  563/564              563/564
BDW                                  417/417              417/417
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 ILK  igt_kms_flip_nonexisting-fb      DMESG_WARN(1, M26)PASS(5, M37M26)      PASS(1, M37)
 ILK  igt_kms_flip_rcs-flip-vs-panning-interruptible      DMESG_WARN(2, M26)PASS(4, M37M26)      PASS(1, M37)
 ILK  igt_kms_flip_rcs-wf_vblank-vs-dpms-interruptible      DMESG_WARN(1, M26)PASS(4, M26M37)      PASS(1, M37)
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