UNIX for Dummies Questions & Answers

Hi friends,
I am currently working on an issue where i should write a program which utilizes Cpu as specified by the user. The function should be provided with an argument ( how much percentage of CPU has to be utilized by the process ) for example CPU(75) should utilize 75% of CPU. The function should be terminated by a signal. Is this feasible ???? guys please help me out. Thanks in advance. is there any linux commands ? all NETBSD functions can be used.

Thanks,
Chandra Mohan .S

Executing function is not visible to the kernel but the process in which its wrapped is available to the external world for communication. I guess this is what you meant right?

Keeping pinging for the load average often if it exceeds or equals commit suicide or restart

Code:

sub get_system_load {
    open(L, '<', '/proc/loadavg') or die "Unable to open /proc/loadavg file <$!>\n";
    my $data = <L>;
    close(L);

    return (split(' ', $data))[0];
}

Look up processor affinity - settask() - will allow you to specify which cpu a process runs on.

A percentage of one single CPU or of all CPUs/Cores/Threads available to it ?
With what sampling rate ? Load is meaningful only as an average value. Instantaneously, a process is either running 100% or 0% of each CPU.

I think am wrong here, what I gave is only a generic load average fetch and controlling based on that. It will really not fetch the utilization of a process bound to a processor.

Load average and CPU load are indeed different metrics.

Oh - ignore the affinity comment. I thought you wanted to designate a cpu for a given process.

Monitoring of cpu usage as a percent by a process on itself is just adding pointless overhead. If you do not want to degrade system performance, then nice the process.

That is why nice exists.

If the process gets 100% cpu, when in a lower priority, it then means nothing else needs it. So it does not degrade overall performance. Plus, 100% cpu utilization in and by itself does not mean the system is overloaded - it could be a background process running at low priority. Things like cpu wait queue length or i/o queue request length are far more important.