regression in 2.6.35.4 'load is to heavy (video subsystem?)'

[Andrew Morton]

On Mon, 30 Aug 2010 10:02:36 +0200
Karsten Mehrhoff <kawime at gmx.de> wrote:

> Using the same .config from 2.6.35.3 to compile 2.5.36.4 results in a  
> heavy load with 2.6.35.4.

A regression within -stable is rather bad.

> Example:
> 
> Difference between 2.6.35.1/2/3 and 2.6.35.4 while watching some videos:
> 2.6.35.4 switches the cpu for flash videos in the browser (opera or  
> iceweasel) or other video outputs to 2200/2400/2600 MHz meanwhile 2.6.35.3  
> (or older) stays at 1000 Mhz. That results in a higher cpu temperature,  
> more power consumption and so one.
> 
> Using other GUI program results in nearly the same problems with 2.6.35.4,  
> so this kernel is unusable for me.
> 
> Results to see the difference for the same action
> 2.6.35.4
> Core0 Temp:  +45.0__C
> Core1 Temp:  +43.0__C
> cpu MHz:	2200.000 or higher
> 
> 2.6.35.3
> Core0 Temp:  +32.0__C
> Core1 Temp:  +31.0__C
> cpu MHz:	1000.000 (max. 1800, but falling back to 1000)
> 
> kernel compiled with 'CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y'
> results for me in 1000, 1800, 2000, 2200, 2400, 2600 MHz.
> 
> I'm not the only one with this problem, other users experienced the same  
> behavior on other systems on 386 systems, i.e. a regression for glxgears  
> about 30% on slower systems. We all uses differnet AMD cpus and nNida  
> graphic controllers. Same results for the nvidia-kernel from the repos or  
> the nVidia driver from nvidia.com.
> 
> There must something be wrong in the video subsystem, which is causing  
> this regression.
> 
> My system (overview using 2.5.35.3):
> =====================
> Processor:	2x AMD Athlon(tm) 64 X2 Dual Core Processor 5000+
> Memory:		 4060MB
> 
> Display
> Resolution:       1920x1080 pixels
> OpenGL Renderer:  GeForce 9500 GT/PCI/SSE2
> X11 Vendor:	      The X.Org Foundation
> Version:          1.7.7
> 
> Version
> Kernel:			Linux 2.6.35.3-kmt (x86_64)
> Compiled:	SMP Mon Aug 23 00:58:37 CEST 2010
> C Library:      GNU C Library version 2.11.2 (stable)
> Default C Compiler: GNU C Compiler version 4.4.5 20100824 (prerelease)  
> (Debian 4.4.4-11)
> Distribution:	Debian GNU/Linux squeeze/sid
> 
> OpenGL
> Vendor:        NVIDIA Corporation
> Renderer:      GeForce 9500 GT/PCI/SSE2
> Version:       3.3.0 NVIDIA 256.44
> Direct Rendering: Yes

I'm not seeing any relevant cpufreq changes in 2.6.35.3 -> 2.6.35.4
(ftp://ftp.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.35.4).  There
were a lot of DRM changes.