Messages in this thread | | | Date | Fri, 8 Jan 1999 17:56:45 +0100 | From | Pavel Machek <> | Subject | Re: Can and should the kernel HZ value be changed? |
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Hi!
> > If you access disks or do other similar tasks (login), and there's > > background process running, you get scheduled at next timer tick - ie. > > 10ms later. This way, I was able to "feel" background while(1); > > processes on my 486/16. I'm currently running some tests (find / in > > fact), to see if this canbe measured in addition to 'felt'. > > no. you get scheduled immediately. You can 'feel' it with a background > process running because starting up a shell is a multi-millisec CPU > excercise even on fast boxes and fully cached, and processes do not start > up with excessive priorities. (see how childs and parents share p->counter > in fork.c) Thus the login is timesharing with the background > process.
You are probably right.
But in this case, increasing HZ _can_ help, because... No, timeslices are expected to remain of same length.
Anyway, there's obscure test p->counter > current->counter + 3, which probably should not be (3 * HZ) / 100. This could do some marginal difference in some cases.
> but after a few seconds, your shell gathers enough 'interactiveness > priority' to not hang when you hit 'Enter'.
That agrees with experiment. I just would like login to be fast even with CPU hogs running in background, automatically (renice them works).
Pavel -- The best software in life is free (not shareware)! Pavel GCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+
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