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disable one processor

emo_2
Occasional Contributor

disable one processor

i have dl385 g5 installed with 2 processors can i desabl one processor from bios ?
3 REPLIES

Re: disable one processor

firts I would ask why would you want to? if its for a program you can set windows to use only one proc. this should eliminate any thread issues. as for the hardware side it woundnt do a thing, if you need to the proc is very easy to remove and should take less than 2 min to remove just remember to wiggle the heatsink from side to side as the thermal grease sets up after a bit.
KarloChacon
Honored Contributor

Re: disable one processor

hi

using BIOS is not possible but using windows yes

I've tested and it works you know when you need to do performance test..

check this you must edit your boot.ini

/NUMPROC=
Specifies the number of CPUs that can be used on a multiprocessor system. Example: /NUMPROC=2 on a four-way system will prevent Windows from using two of the four processors.

or

/numproc=number
This switch sets the number of processors that Windows will run at startup. With this switch, you can force a multiprocessor system to use only the quantity of processors (number) that you specify. This switch can help you troubleshoot performance problems and defective CPUs.

http://support.microsoft.com/kb/833721


so if you have for example 2 dual cores you will have 4 logicals CPUs you if you want to test only 1 physical CPU you must add
this

/numproc=2

is it windows?

regards
Didn't your momma teach you to say thanks!
rick jones
Honored Contributor

Re: disable one processor

Be careful with numproc or maxcpus (on Linux) - perhaps CPU numbering is different under Windows, but if it isn't then you should know that if you have multiple core processors the numbering bounces from socket to socket, so in the example of my DL385G2 with a pair of 2220s CPUs/cores 0 and 2 are in processor/socket 0 and CPUs/cores 1 and 3 are in processor/socket 1.

If I were to boot a Linux kernel with maxcpus=2 it would use CPUs/cores 0 and 1 and so would be making use of the services of both sockets, which would not be the same as if I'd just bought a system with one socket populated.

In another discussion I've learned that if I want just the cores of the one processor/socket, short of pulling the second processor from the socket, under Linux I would do:

# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo 0 > /sys/devices/system/cpu/cpu3/online

Perhaps there is something like that for Windows.

One day when/if more x86 stuff migrates to EFI perhaps it will be possible to use the EFI utility cpuconfig as found on the Integrity systems to disable a processor/socket at the "firmware" level before the OS is booted.
there is no rest for the wicked yet the virtuous have no pillows