Bug 65694 - [HSW] FBC didn’t save power for game workload
Summary: [HSW] FBC didn’t save power for game workload
Status: CLOSED NOTABUG
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-06-13 02:08 UTC by Liu Tienan
Modified: 2017-07-24 22:58 UTC (History)
2 users (show)

See Also:
i915 platform:
i915 features:

Attachments

Description Liu Tienan 2013-06-13 02:08:23 UTC 
System Environment:
----------------------------------------
Platform: HSW
Libdrm:                       (master)libdrm-2.4.45-3-

g3586337f3703ce4833a375f66b08df064a1cec28
Mesa:                          (master)f6beb4c6b647b0d5077c7abd6c99cdaba6e0c112
Xserver:                      (master)xorg-server-1.14.99.1-82-

g7e97166c4fc38076b6224e4dbdd632b43444149f
Xf86_video_intel:         (master)2.21.6-47-gd6c30d1d4df6bcdfa075bd29da7c8aabee20774c
Cairo:                         (master)631bf299256e11a17511977f357e0353fb5615f7
Libva:                          (staging)880c916092c6d68096c95e49405714d8a21f9322
Libva_intel_driver:        (staging)0a5cfdab47c788569feb0a3e4293906687523f88      
Kernel:                        (drm-intel-nightly) 675fa342aa3a54af0a81f23809fff9590dfb6fc1


Test result:
----------------------------------------      
HSW-ult      FBC disable Average_watt       FBC enable Average_watt          
game         21                             21
    
IVB          FBC disable Average_watt       FBC enable Average_watt
game         34.8                           34.7 

Findings:
----------------------------------------
For game, FBC saved 0.1w on IVB, but didn’t saved power on HSW.
FBC pass/fail criteria is 0.1-0.2w.
Comment 1 Chris Wilson 2013-06-13 07:25:00 UTC 
In the game workload, the criteria is for FBC not to consume more power. Since every frame requires recompression (costing power), and ideally the game is running at the vertical refresh, there is no power saving from used the same compressed data for more than one refresh. For this reason, FBC is turned off under this workload.
Comment 2 Ouping Zhang 2013-06-13 07:34:46 UTC 
But I confused why game workload saved 0.1w power, and HSW didn't.
(In reply to comment #1)
> In the game workload, the criteria is for FBC not to consume more power.
> Since every frame requires recompression (costing power), and ideally the
> game is running at the vertical refresh, there is no power saving from used
> the same compressed data for more than one refresh. For this reason, FBC is
> turned off under this workload.

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