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Old 08-27-2008, 11:23 PM
Kevin Rolfes
 
Default Bug#496850: linux-image-2.6.18-6-486: bogomips reduced from 100 to 20 after package upgrade

Package: linux-image-2.6.18-6-486
Version: 2.6.18.dfsg.1-22etch2
Severity: minor


I think this is minor, but it caught my attention and I thought the
package maintainer might want to know about it. Upgrading this
package from 2.6.18.dfsg.1-22 to 2.6.18.dfsg.1-22etch2 caused the
bogomips benchmark to drop from 99.07 to 20.03 on a Vortex86SX
based computer.

Downgrading this package back to 2.6.18.dfsg-1-22 (using
"apt-get install linux-image-2.6.18-6-486=2.6.18.dfsg.1-22"),
and changing nothing else, restored the bogomips rating back to 99.07.

I do not know if the computer actually ran slower. I didn't notice
a difference while using it, it was just the bogomips number that
caught my attention. If additional testing would be helpful, please
suggest something that would run on a minimal (command-line only) Etch
installation.

The computer is an Ebox 2300SX, which is a tiny x86 computer that
contains a Vortex86SX processor running at 300MHz. (More CPU info at
http://www.dmp.com.tw/tech/vortex86sx/)
I installed Debian Etch 4.0.r4 which came with version
2.6.18.dfsg.1-22 of the package linux-image-2.6.18-6-486. During
startup, the computer reported 99.07 BogoMIPS which was in line
with other reported ratings (i.e. 1/3 the processor clock).

After the installation, I added security.debian.org to
/etc/apt/sources.list and used apt-get to upgrade the installed
packages. According to the time stamps of the installed files
and the log files, it was the next reboot that showed the
reduced BogoMIPS.

Here is /proc/cpuinfo with the rolled back (2.6.18.dfsg.1-22)
version of linux-images:

processor : 0
vendor_id : unknown
cpu family : 4
model : 0
model name : 486
stepping : unknown
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : no
fpu_exception : no
cpuid level : -1
wp : yes
flags :
bogomips : 99.07

Thanks and best regards,
Kevin

-- System Information:
Debian Release: 4.0
APT prefers stable
APT policy: (500, 'stable')
Architecture: i386 (i486)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-6-486
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)



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Old 12-21-2008, 12:22 AM
Moritz Muehlenhoff
 
Default Bug#496850: linux-image-2.6.18-6-486: bogomips reduced from 100 to 20 after package upgrade

On Wed, Aug 27, 2008 at 11:23:11PM +0000, Kevin Rolfes wrote:
> Package: linux-image-2.6.18-6-486
> Version: 2.6.18.dfsg.1-22etch2
> Severity: minor
>
>
> I think this is minor, but it caught my attention and I thought the
> package maintainer might want to know about it. Upgrading this
> package from 2.6.18.dfsg.1-22 to 2.6.18.dfsg.1-22etch2 caused the
> bogomips benchmark to drop from 99.07 to 20.03 on a Vortex86SX
> based computer.
>
> Downgrading this package back to 2.6.18.dfsg-1-22 (using
> "apt-get install linux-image-2.6.18-6-486=2.6.18.dfsg.1-22"),
> and changing nothing else, restored the bogomips rating back to 99.07.
>
> I do not know if the computer actually ran slower. I didn't notice
> a difference while using it, it was just the bogomips number that
> caught my attention. If additional testing would be helpful, please
> suggest something that would run on a minimal (command-line only) Etch
> installation.
>
> The computer is an Ebox 2300SX, which is a tiny x86 computer that
> contains a Vortex86SX processor running at 300MHz. (More CPU info at
> http://www.dmp.com.tw/tech/vortex86sx/)
> I installed Debian Etch 4.0.r4 which came with version
> 2.6.18.dfsg.1-22 of the package linux-image-2.6.18-6-486. During
> startup, the computer reported 99.07 BogoMIPS which was in line
> with other reported ratings (i.e. 1/3 the processor clock).
>
> After the installation, I added security.debian.org to
> /etc/apt/sources.list and used apt-get to upgrade the installed
> packages. According to the time stamps of the installed files
> and the log files, it was the next reboot that showed the
> reduced BogoMIPS.
>
> Here is /proc/cpuinfo with the rolled back (2.6.18.dfsg.1-22)
> version of linux-images:
>
> processor : 0
> vendor_id : unknown
> cpu family : 4
> model : 0
> model name : 486
> stepping : unknown
> fdiv_bug : no
> hlt_bug : no
> f00f_bug : no
> coma_bug : no
> fpu : no
> fpu_exception : no
> cpuid level : -1
> wp : yes
> flags :
> bogomips : 99.07

Does this error still occur with more recent kernel versions?

If you're running Etch, could you try to reproduce this bug
with the 2.6.24 based kernel added in 4.0r4?
http://packages.qa.debian.org/l/linux-2.6.24.html

Cheers,
Moritz



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Old 12-21-2008, 03:56 AM
Kevin Rolfes
 
Default Bug#496850: linux-image-2.6.18-6-486: bogomips reduced from 100 to 20 after package upgrade

> > I think this is minor, but it caught my attention and I thought the
> > package maintainer might want to know about it. Upgrading this
> > package from 2.6.18.dfsg.1-22 to 2.6.18.dfsg.1-22etch2 caused the
> > bogomips benchmark to drop from 99.07 to 20.03 on a Vortex86SX
> > based computer.

...

> Does this error still occur with more recent kernel versions?

Yes, I checked today with 2.6.18.dfsg.1-23etch1, and /proc/cpuinfo
is reporting 22.97 bogomips.

> If you're running Etch, could you try to reproduce this bug
> with the 2.6.24 based kernel added in 4.0r4?
> http://packages.qa.debian.org/l/linux-2.6.24.html

This kernel will not boot for me. After loading the kernel the
computer dies with a kernel panic. The call trace begins with
"kernel_init+0x189/0231" and ends in "unknown_bootoption+0x0/0x195".
The last line is
"Kernel panic - not syncing: Attempted to kill the idle task!"
Any pointers for further troubleshooting would be welcome.

I am using LILO with append="no387 pnpbios=off" if that matters.

Best regards,
Kevin




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Old 02-10-2009, 02:28 AM
Kevin Rolfes
 
Default Bug#496850: linux-image-2.6.18-6-486: bogomips reduced from 100 to 20 after package upgrade

I believe this is resolved with version 2.6.18.dfsg.1-24 of
linux-image-2.6.18-6.486:

# cat /proc/cpuinfo
processor : 0
vendor_id : unknown
cpu family : 4
model : 0
model name : 486
stepping : unknown
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : no
fpu_exception : no
cpuid level : -1
wp : yes
flags :
bogomips : 97.79

Best regards,
Kevin




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