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    SubjectRe: system call for process information?
    Hi Alexander, Nathan and all!

    Thanks for your great answers! First of all - I was not REALLY proposing
    to include this system call in the kernel - I just wanted to hear some pro
    and contra - so, thanks again for your explanations! I started yesterday
    sketching the required functions, will have to retreat to reading top & ps
    sources, btw, apart from these 2 obvious sources, what else would you
    suggest to look through for a good implementation of CPU-utilization
    calculator as well as other process (multithreaded, SMP,...) statistics?
    Portable (POSIX), maybe some documentation, not just sources?

    Thanks
    Guennadi

    On Mon, 12 Mar 2001, Alexander Viro wrote:

    > On Mon, 12 Mar 2001, Nathan Paul Simons wrote:
    >
    > > On Mon, Mar 12, 2001 at 09:21:37PM +0000, Guennadi Liakhovetski wrote:
    > > > CPU utilisation. Each new application has to calculate it (ps, top, qps,
    > > > kps, various sysmons, procmons, etc.). Wouldn't it be worth it having a
    > > > syscall for that? Wouldn't it be more optimal?
    >
    > The first rule of optimization: don't. I.e. optimizing something that
    > is not a bottleneck is pointless.
    >
    > > No, it wouldn't be worth it because you're talking about
    > > sacrificing simplicity and kernel speed in favor of functionality.
    >
    > Or, in that case, in favour of nothing. It doesn't add any functionality.
    >
    > > This has been know to lead to "bloat-ware". Every new syscall you
    > > add takes just a little bit more time and space in the kernel, and
    > > when only a small number of programs will be using it, it's really
    > > not worth it. This time and space may not be large, but once you
    > > get _your_ syscall added, why can't everyone else get theirs added
    > > as well? And so, after making about a thousand specialized syscalls
    > > standard in the kernel, you end up with IRIX (from what I've heard).
    >
    > In that case there is much simpler argument.
    >
    > If your program checks the system load so often that converting results
    > from ASCII to integers takes noticable time - all you are measuring
    > is the load created by that program. In other words, any program that
    > would get any speedup from such syscall is absolutely worthless, since
    > the load created by measurement will drown the load you are trying
    > to measure.
    >
    > End of story. It's not only unnecessary and tasteless, it's
    > useless.
    > Cheers,
    > Al
    >
    >

    ___

    Dr. Guennadi V. Liakhovetski
    Department of Applied Mathematics
    University of Sheffield, U.K.
    email: G.Liakhovetski@sheffield.ac.uk


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