Messages in this thread | | | Date | Tue, 16 Apr 2002 08:31:45 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: Why HZ on i386 is 100 ? |
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On Tue, 16 Apr 2002, William Lee Irwin III wrote:
> On Tue, Apr 16, 2002 at 09:47:48AM +0200, Olaf Fraczyk wrote: > > Hi, > > I would like to know why exactly this value was choosen. > > Is it safe to change it to eg. 1024? Will it break anything? > > What else should I change to get it working: > > CLOCKS_PER_SEC? > > Please CC me. > > Regards, > > Olaf Fraczyk > > I tried a few times running with HZ == 1024 for some testing (or I guess > just to see what happened). I didn't see any problems, even without the > obscure CLOCKS_PER_SEC ELF business. > > > Cheers, > Bill > -
On Version 2.3.17, with a 600 MHz SMP Pentium, I set HZ to 1024 and recompiled everything. There was no apparent difference in performance or "feel".
Note that HZ represents the rate at which a CPU-bound process may get the CPU taken away. Real-world tasks are more likely to be doing I/O, thus surrendering the CPU, before this relatively long time-slice expires. I don't think you will find any difference in performance with real-world tasks. FYI, the Alpha uses 1024 simply because the timer-chip can't divide down to 100 Hz.
Cheers, Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
Windows-2000/Professional isn't.
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