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

From: Andrew Morton
Date: Tue Sep 21 2010 - 19:50:25 EST


On Mon, 30 Aug 2010 10:02:36 +0200
Karsten Mehrhoff <kawime@xxxxxx> 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.


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