macsmith
Posts: 13
Joined: Fri Dec 30, 2011 5:12 pm

Bogus BogoMips?

Mon May 06, 2013 9:06 am

I was looking at the details of buying an Mpeg-2 license and how to determine the serial number of the Pi: http://www.raspberrypi.com/vc-1-license-key/. As well as the serial number, this also lists the measured BogoMips of the device.

Trouble is, the foundation's serial #d Raspberry Pi is shown to have a rating of 697.95 BogoMips, whereas my, much more modern(!), Raspberry Pi only achieves 464.48, a mere 66% of the original.

What's going on?

Ian

remsnet
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Location: Planet Gaia
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Re: Bogus BogoMips?

Mon May 06, 2013 9:29 am

macsmith wrote:I was looking at the details of buying an Mpeg-2 license and how to determine the serial number of the Pi: http://www.raspberrypi.com/vc-1-license-key/. As well as the serial number, this also lists the measured BogoMips of the device.

Trouble is, the foundation's serial #d Raspberry Pi is shown to have a rating of 697.95 BogoMips, whereas my, much more modern(!), Raspberry Pi only achieves 464.48, a mere 66% of the original.

What's going on?

Ian
1 - the ~700 Bogos are only when overclocked
for stabiliy of your PI you shuold NOT overclock the PI.
Especialy not - when you have sd cards with class 6 and 10 in use.

1.1- you can Ignore the BogoMips on RPI - its meaningless untill you add an RT Clock
1.2 - BogoMips on 3.8.x kernel has been changed


2 - find the serial number of your PI

Code: Select all

 cat /proc/cpuinfo | tail -1 | awk '{print $3}'

macsmith
Posts: 13
Joined: Fri Dec 30, 2011 5:12 pm

Re: Bogus BogoMips?

Mon May 06, 2013 12:50 pm

looks like any overclocking starts after the bogomips measurement, see http://www.raspberrypi.org/phpBB3/viewt ... 66&t=26616. So probably the changes to the kernel which have caused it.

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abishur
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Re: Bogus BogoMips?

Mon May 06, 2013 1:38 pm

remsnet wrote:
1 - the ~700 Bogos are only when overclocked
for stabiliy of your PI you shuold NOT overclock the PI.
Especialy not - when you have sd cards with class 6 and 10 in use.
Actually the pi can safely and stably be overclocked. Even though mechanically everything is the same between two pis, the degree by which they can be overclocked will vary. On all the pi's I've tested, I've been able to push 100% of them to at least the 800 mHz level with no over voltage with no stability issues whatsoever even with my class 10 SD card. If you don't mind getting your hands dirty, you can place a capacitor between to of the pins on the sd card and that seems to fix certain instabilities when using the overvoltage (I don't remember which two, but the information is here on the forum).
Dear forum: Play nice ;-)

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