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Beagleboard xM - Bogomips are very low

DISCUSSION Guillaume Gardet 3 participants 4 messages Mar 19, 2013 – Mar 20, 2013

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#0 lore raw

Hi,

On a Beagleboard xM rev. B, I noticed that vanilla kernel 3.4.6 have the folowing bogomips for 300MHz and 800 MHz operations: 262.08 and 700.57.

With kernel 3.7.10, I have : 175.65 and 467.41 bogompis.

Any idea why bogomips are so low now?

Guillaume

#1 lore raw
Quoted 7 lines · Guillaume Gardet

Hi,

On a Beagleboard xM rev. B, I noticed that vanilla kernel 3.4.6 have the folowing bogomips for 300MHz and 800 MHz operations: 262.08 and 700.57.

With kernel 3.7.10, I have : 175.65 and 467.41 bogompis.

Any idea why bogomips are so low now?

using my DTS cpufreq series (which I am about to post to linux-omap):
https://github.com/nmenon/linux-2.6-playground/commits/push/cpufreq-cpu0-omap-all-v2
and a test script:
http://pastebin.com/zrr8ptge

I See (3.9-rc3):
http://pastebin.com/4JCV3dnX

bogomips@ boot:
BogoMIPS : 395.67
Boot scaling frequency =600000
TESTING for 1 seconds at 300000 current scaling frequency(for 300000) =300000 bogomips@ frequency 300000:
BogoMIPS : 197.83
TESTING for 1 seconds at 600000 current scaling frequency(for 600000) =600000 bogomips@ frequency 600000:
BogoMIPS : 395.67
TESTING for 1 seconds at 800000 current scaling frequency(for 800000) =800000 bogomips@ frequency 800000:
BogoMIPS : 527.56

Signature · 2 lines
Regards,
Nishanth Menon
#2 lore raw
In reply to Guillaume Gardet
Quoted 9 lines · Guillaume Gardet

Hi,

On a Beagleboard xM rev. B, I noticed that vanilla kernel 3.4.6 have the folowing bogomips for 300MHz and 800 MHz operations: 262.08 and 700.57.

With kernel 3.7.10, I have : 175.65 and 467.41 bogompis.

Any idea why bogomips are so low now?

I believe this is the reason for the BogoMIPS change:

http://www.spinics.net/lists/arm-kernel/msg221672.html

It looks like BogoMIPS reporting changed because of the delay routine patch introduced in 3.6. So the change in BogoMIPS is real, but should not be a concern.

frank agius

Quoted 7 lines

Guillaume

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#3 lore raw
Quoted 8 lines · Frank Agius
Quoted 7 lines · Guillaume Gardet

Hi,

On a Beagleboard xM rev. B, I noticed that vanilla kernel 3.4.6 have the folowing bogomips for 300MHz and 800 MHz operations: 262.08 and 700.57.

With kernel 3.7.10, I have : 175.65 and 467.41 bogompis.

Quoted 8 lines
Quoted 2 lines

Any idea why bogomips are so low now?

I believe this is the reason for the BogoMIPS change:

http://www.spinics.net/lists/arm-kernel/msg221672.html

It looks like BogoMIPS reporting changed because of the delay routine patch introduced in 3.6. So the change in BogoMIPS is real, but should not be a concern.

Thanks for the pointer. So, it should not affect performances. I will try to bench it, to be sure there is no hidden problem.

Thanks.

Guillaume

Quoted 12 lines

frank agius

Quoted 7 lines

Guillaume

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