Bug 65154

Summary:	[IVB/HSW bisected]Lightsmark v2008 performance reduced by ~8%
Product:	Mesa	Reporter:	meng <mengmeng.meng>
Component:	Drivers/DRI/i965	Assignee:	Eric Anholt <eric>
Status:	VERIFIED FIXED	QA Contact:
Severity:	major
Priority:	high	CC:	eric, idr
Version:	unspecified
Hardware:	All
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description meng 2013-05-30 02:46:17 UTC

System Environment:       
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Platform:  HSW/IVB
Mesa:    (master)4dea6cf21557bcd3bbab3402e19e19f665d7e177
Kernel:	 (drm-intel-nightly) 0888e7a120fbc70af0867041abccc72c753ed810

Bug detailed description:
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 Lightsmark v2008 performace reduced by ~8% on HSW/IVB. The problem exists on X raw and gnome-session. It’s Mesa regression, bisecting show the first bad commit is that:

commit e845c5cf7abce55759501a473459aff3bf25c9ca
Author: Eric Anholt <eric@anholt.net>
Date:   Thu May 23 16:58:58 2013 -0700

    intel: Make a temporary miptree for the blit path of miptree mapping.

Performance detail 
HSW: X raw.1920x11080
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Mesa 9.2.0 (git-4a13bee): 77.72
Mesa 9.2.0 (git-e845c5c): 71.32

Reproduce steps:
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1. xinit&
2. vblank_mode=0 ./backend silent 1920x1080

Comment 1 meng 2013-05-30 07:28:51 UTC

The Mesa patch also caused Open Arena v0.8.8 reduced by 12% ±8%  on IVB (not on HSW).
Performance detail
IVB, gnome-session with compositing:1920x1080 and SNA
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Mesa 9.2.0 (git-4a13bee) average result:  36.6 (36.4,36.7,36.7)
Mesa 9.2.0 (git-e845c5c) average result:  31.97( 34.5,30.7,30.7)

Comment 2 Gordon Jin 2013-06-03 14:03:44 UTC

Eric, can you reproduce this?

Comment 3 Eric Anholt 2013-06-03 21:31:02 UTC

A patch was already on mesa-dev undergoing review last thursday.  I do want to say thanks for the quick report of the performance regression (within 2 days after it landed), and the improved turnaround here really helped get it fixed quickly.  Nagging on bugs for developers to reproduce them is a major demotivator, though.

commit f96de8ad9622d42ce54feedd246967c73d1206cd
Author: Eric Anholt <eric@anholt.net>
Date:   Thu May 30 09:43:45 2013 -0700

    intel: Fix performance regression from miptree blit changes.

Comment 4 meng 2013-06-04 00:38:51 UTC

Verified it with Mesa 9.2.0 (git-f96de8a).

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