Bug 62710 - [IVB bisected]x11perf performance reduced by 40%
Summary: [IVB bisected]x11perf performance reduced by 40%
Status: CLOSED NOTABUG
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-03-25 03:38 UTC by meng
Modified: 2017-07-06 17:37 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

Attachments

Description meng 2013-03-25 03:38:20 UTC 
System Environment:       
--------------------------
Platform:IVB
Libdrm: (master)libdrm-2.4.42-7-g36a2daad2416ad55a859c483b0d7ed93a5eff6e0
Mesa:   (9.1)e6616948b74531eae3137585b3ae35a1fc0f8174
Xserver:(server-1.13-branch)xorg-server-1.13.3
Xf86_video_intel:(master)2.21.5-1-g9f8e86800345d19785eae2dd2099dd7d61a7a3b3
Kernel: (drm-intel-fixes) c12aba5aa0e60b7947bc8b6ea25ef55c4acf81a4

Bug detailed description:
-----------------------------
x11perf performance reduced by 40% on IVB. The problem exists on both xinit and gnome-session. It's kernel regression, by bisected show 3b4f819d5eac94ba8fe5 is the first bad commit.

commit 3b4f819d5eac94ba8fe5e8c061f6dabfe8d7b22c
Author: Takashi Iwai <tiwai@suse.de>
Date:   Mon Mar 11 18:40:16 2013 +0100
    Revert "drm/i915: try to train DP even harder"

Performance data
-------------------
x11perf -aa10text on IVB.
                   gnome-session         xinit               
good(3118a)        3620000.0/sec        4230000.0/sec       
bad(3b4f81)        2300000.0/sec        2480000.0/sec

Reproduce steps:
----------------------------
1, xinit&
2, vblank_mode=0 x11perf -aa10text
Comment 1 Chris Wilson 2013-03-25 09:39:10 UTC 
Still in excess of 20MGlyphs/s here.
Comment 2 Jani Nikula 2013-03-25 13:10:07 UTC 
(In reply to comment #0)
> x11perf performance reduced by 40% on IVB. The problem exists on both xinit
> and gnome-session. It's kernel regression, by bisected show
> 3b4f819d5eac94ba8fe5 is the first bad commit.
> 
> commit 3b4f819d5eac94ba8fe5e8c061f6dabfe8d7b22c
> Author: Takashi Iwai <tiwai@suse.de>
> Date:   Mon Mar 11 18:40:16 2013 +0100
>     Revert "drm/i915: try to train DP even harder"

That commit seems very unlikely to cause performance regressions.
Comment 3 meng 2013-03-26 06:39:11 UTC 
The kernel configure changed cause the x11perf performance reduced, so close it.
Comment 4 Daniel Vetter 2013-03-26 12:32:38 UTC 
Can you please attach the diff in .config which causes this? This isn't the first time where a random .config change caused a performance regression, we need to get this kinds of effects under control.

Since if we can't control for those random 40% spikes in different directions, performance testing isn't that useful.
Comment 5 meng 2013-03-27 01:44:28 UTC 
It's caused by the kernel configure “CONFIG_PROVE_LOCKING” that is the same as bug 54795.
Comment 6 meng 2014-07-18 02:29:55 UTC 
Closed it.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.