Constraining CPU usage

Shane Ambler Shane at
Sat Dec 3 04:16:54 PST 2005

On 3/12/2005 3:14, "Arne Woerner" <arne_woerner at> wrote:

> --- Nash Nipples <trashy_bumper at> wrote:
>> It seems i cannot get a clear answer wherther it
>> is possible to limit a CPU usage by a user process
>> and should i do that at all.
> Why should somebody want to keep CPU usage of a process below a
> certain value (e. g. 20%)?

Well if your machine isn't smp enabled (specifically pre-HTT) then one
process can slow the server down to a point where your web/databse server
can't get processor time to give a response - effectively making it non
existent for the duration.

Some tasks such as getting awstat to update and create stats pages are not a
priority and can take as long as they need.

(if you can't guess this is a problem I am just starting to look into)

>> As you can see in the figure above, renicing wont work.
> Why? Obviously there is no or nearly no other process, that wants
> to run, so your "tar" process runs as fast as possible in order to
> finish as soon as possible...
> Reniceing to a positive nice-value means that this process gets
> the processor less often than other processes, who want to run...
>> Any hints? What to read? Thank you.
> You could try idprio(1) against your tar process. That makes sure,
> that your tar process waits, when other processes (non idprio
> processes) want to run...
> -Arne
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Shane Ambler
Sales Department
Shane at

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