Messages in this thread | | | Date | Tue, 13 Mar 2001 09:55:33 +0000 (GMT) | From | Guennadi Liakhovetski <> | Subject | Re: system call for process information? |
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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 > >
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Dr. Guennadi V. Liakhovetski Department of Applied Mathematics University of Sheffield, U.K. email: G.Liakhovetski@sheffield.ac.uk
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