Re: Regarding Power macG4
Re: Regarding Power macG4
- Subject: Re: Regarding Power macG4
- From: Christopher Nebel <email@hidden>
- Date: Mon, 5 Aug 2002 13:01:34 -0700
On Sunday, August 4, 2002, at 06:49 PM, tampi banerjee wrote:
I want to measure the performance of some DSP algorithms in a 1 Ghz
Power Mac G4. I have to evaluate the performance using only one
processor . however the Power Mac G4 1 ghz comes with a dual
processor.Is there any way to power off one of them while evaluating
the performance ? or , can we in any way make out the performance of
one processor only (even after the two have worked) by some mechanism?
This is way lower-level than AppleScript can deal with, but it is
possible:
1. Get into Open Firmware by restarting and holding down cmd-opt-O-F
keys until you see the screen light up and the Open Firmware prompt
appears.
2. Type the following:
setenv boot-args cpus=1
mac-boot
Congratulations, you have now disabled one cpu. To turn it back on, do
the same thing but say "cpus=2" instead.
Bear in mind that unless your code is multi-threaded, it's only going
to use one cpu at a time anyway. However, it will hop from one to the
other as the scheduler feels like it, so cache locality may affect the
timing.
--Chris Nebel
AppleScript Engineering
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