Bug 101677

Summary: [GEN7/8] 1-10% perf drop on in offscreen benchmarks with "intel/isl: Only create a CCS buffer if the image supports rendering"
Product: Mesa Reporter: Eero Tamminen <eero.t.tamminen>
Component: Drivers/DRI/i965Assignee: Nanley Chery <nanleychery>
Status: VERIFIED FIXED QA Contact: Intel 3D Bugs Mailing List <intel-3d-bugs>
Severity: normal    
Priority: medium    
Version: git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:

Description Eero Tamminen 2017-07-03 14:23:08 UTC 
Performance in all (GPU bound) GLB 2.7 & GfxBench v4.0 offscreen benchmarks dropped on 26th June, with a commit that ezbench bisected to:
-------------------------------------------------------
commit 8aaa13467dc289d35dc7900ab9fab9a7689c4178
Author:     Nanley Chery <nanley.g.chery@intel.com>
AuthorDate: Mon Mar 6 14:27:44 2017 -0800
Commit:     Nanley Chery <nanley.g.chery@intel.com>
CommitDate: Mon Jun 26 11:09:12 2017 -0700

    intel/isl: Only create a CCS buffer if the image supports rendering
    
    v2: Omit the commit message.
    
    Signed-off-by: Nanley Chery <nanley.g.chery@intel.com>
    Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
    Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
-------------------------------------------------------

On BDW GT3, GLB 2.7 Egypt offscreen test drops by ~10% and GLB 2.7 Fill offscreen & GfxBench v4.0 Tessellation offscreen drop by ~7%.

Fairly similar drops are visible on BDW GT2 and somewhat smaller drops on BSW, HSW GT2 and BYT.
Comment 1 Eero Tamminen 2017-07-05 11:44:05 UTC 
CarChase onscreen performance also drops on all of these.  On BSW performance drops also in onscreen versions of T-Rex & Egypt.
Comment 2 Nanley Chery 2017-07-05 19:45:07 UTC 
Thank you for catching this regression! There was a faulty assumption behind the patch. I have the fix going through jenkins.
Comment 3 Nanley Chery 2017-07-06 20:14:07 UTC 
The patches are on the list: https://patchwork.freedesktop.org/series/26943/
Comment 4 Eero Tamminen 2017-07-07 15:30:37 UTC 
Verified that patches fix the GL performance drop.  Please push at least the revert as soon as possible.

(Maybe in the Vulkan driver perf output patch it could state what is "This image format"?)
Comment 5 Eero Tamminen 2017-07-07 15:33:24 UTC 
Noticed more cases which this regressed.  On GEN7, also GpuTest Triangle onscreen & offscreen cases regressed.
Comment 6 Nanley Chery 2017-07-07 21:30:37 UTC 
I just pushed the revert patch.
Comment 7 Eero Tamminen 2017-07-10 09:50:02 UTC 
Verified, perf is fine again.  Thanks!

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