Messages in this thread | | | Date | Mon, 19 Apr 1999 16:40:30 +0200 | From | Michael Mess <> | Subject | Wrong timing in Linux 2.2.6 with smp? |
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I noticed that some timings seem to be wrong in Linux 2.2.6 with SMP compiled in.
<michael@rakete>:~>date ; sleep 10 ; date Mon Apr 19 12:38:42 CEST 1999 Mon Apr 19 12:38:52 CEST 1999
These commands needed 55 seconds to finish! The clock is also going wrong.
<michael@rakete>:~>uptime ; date 12:45pm up 49 min, 3 users, load average: 1.80, 1.36, 0.63 Mon Apr 19 12:45:35 CEST 1999
Now it is really 16:20 MEST. But I don't know if the computer clock was OK on boot and if the given value (12:45 CEST) is MEST (Median European Summer Time) or if only the BIOS clock is MEST and this value was calculated wrong. If you need reliable information about the clock, ask me and I will make some experiments to find out.
These things seem to be independent from the system load. XOSVIEW sometimes shows me a cpu load of > 100%. These values are always a multiple of 10. When I load the system for testpurposes, I open some shells and type in: <michael@michael>:~>while true; do true ; done On my 486 I get a CPU=100% and LOAD=1.
On my Dual Pentium II with SMP-kernel with 4 shells doing such "work" (to assure that the cpus are really 100% loaded) I get a load between 2.8 and 3.2 and CPU0=550% and CPU1=550%. Strange, isn't it? There seems to be a magic factor of 5.5
The sceduling seems to be slow, too. Sometimes the system needs some time if you press ctrl-c to cancel a command.
If you get a beep (console or X), it sounds longer than usual. If I set the beep in kpanel to 1000ms length, it lasts 11 seconds.
<michael@rakete>:~>uname -a Linux rakete 2.2.6 #7 SMP Sun Apr 18 18:33:05 CEST 1999 i686 unknown <michael@rakete>:~>
<michael@rakete>:~>cat work.cc void main() {
int a=0; while (1) {
a=a+2; }
} <michael@rakete>:~> Two processes of these program running give me a load of 2.0 if running some time. 4 of them give me a load of 3.0
Greetings, Michael
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