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Solaris 7 x86 - stop cpu 0

Posted on 2000-05-02
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Last Modified: 2013-12-27
Hi.

I have a dual-PII server with Solaris 7 on it. I need to perform maintenance task by stopping each CPU for a while (to cool down), while the other works.
I have no problem stopping cpu 1 with
  psradm -f 1
command, but, when i try to stop cpu 0 by a similar command, i get:
  psradm: processor 0: Device busy

I guess that this processor is locked by kernel, or something like that.
So, here is the question:
IS IT POSSIBLE to stop cpu 0 and run the system on cpu 1 only?

If someone tells me that it is possible, i will raise points to 200 for the answer HOW can i do it...

Regards,
Tal


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Question by:sereda
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jlevie earned 50 total points
ID: 2769164
I don't think so. I suspect that this is an intel platform problem relating to the way multiple cpu's are implemented. I vaguely recall that you can't even boot an intel multi-processor without having the first processor installed.

I guess I don't understand why you should need to "cool down" one of the processors. It would seem to me that would imply that you've got a problem with insuffucient air flow through the box and additional fans would be the logical solution.
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by:sereda
ID: 2769209
Thanks for comment, jlevie,
waiting for other opinions...

As for cooling down - yep, additional fans will do the work, but stopping cpus has some advantages: first, it's a little bit more flexible and reliable (imho) and second, and most important, you don't have to go to the server's location and stop it.
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by:festive
ID: 2773408
As far as I am aware no! you must have a cpu dedicated to the OS, I believe that this is the first one it finds.

you should look at the cryotech cooling system... very nice.

I am sorry to say (are there any electrical engineers out there) I believe that your attentions to doing this may be misguided, ie I do not believe that deselecting a CPU will allow it to cool, as the circuitry to the unit cannot be removed and the overclocking (assuming that there is some) will be BUS-WIDE regardless of the usage of the CPU.

Solaris uses a process called symmetric multi-processing (for example) which enables it to spread low-level cpu instructions accross CPU's.

Please forgive me if I have misread your intentions, But I would (given the above) be unsure as to why you would want to convert a multi-cpu machine back into a single-cpu system anyway.
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Author Comment

by:sereda
ID: 2773505
Well, the reasons i thought of is that CPU is heating not just because it's power-on and bus activity takes place, but because it constantly runs commands.

As a proof, i can think of different OSes (say, DOS and OS/2) - the latter is sending HLT instruction (or something) to the processor while it's not needed (idle cycle), and actually CPU stays pretty cool under slight load.

So, i guessed that stopping it may help to cool it down.

Seems like it's not really possible to turn off CPU 0... Well, let's wait a little bit longer...

Approach to the problem is that server is physically unaccessible.
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by:ianB
ID: 2855584
We have opened up a new Solaris Topic Area.  

To increase the visibility of questions, we moved questions we felt
appropriate to the new Solaris Topic Area where they will be easier for
Solaris experts to find and answer. You may view your question at
http://www.experts-exchange.com/Computers/Operating_Systems/Solaris/ 

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by:sereda
ID: 2858169
Comment accepted as answer
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by:sereda
ID: 2858170
Well, it seems that there's no way to stop CPU 0 on intel platform. :(
Thanks for participating though :)
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