Messages in this thread | | | From | "David Luyer" <> | Subject | RE: Linux 2.4.19ac3rc3 on IBM x330/x340 SMP - "ps" time skew | Date | Wed, 31 Jul 2002 21:01:45 +1000 |
| |
I wrote:
> In Linux 2.4.19ac3rc3 on IBM x330/x340 SMP systems we're seeing this: > > luyer@praxis8:~$ ps auxwww | tail -1 > luyer 1025 0.0 0.0 1276 352 pts/2 S Aug06 0:00 tail -1 > luyer@praxis8:~$ date > Wed Jul 31 12:35:16 EST 2002
(UP systems are fine, SMP have this problem)
Reason:
luyer@praxis8:~$ ps --info 2>&1 | grep Hertz EUID=111 TTY=136,3 Hertz=50
procps is getting the hertz value wrong, it's computing it as:
h = (unsigned long)( (double)jiffies/seconds/smp_num_cpus );
but we're only getting timer interrupts on CPU 0, and hence jiffies is only incrementing once per 100th of a second.
luyer@praxis8:~/procps/procps-2.0.7.orig/proc$ cat /proc/interrupts CPU0 CPU1 0: 52459351 0 local-APIC-edge timer 1: 0 2 IO-APIC-edge keyboard 2: 0 0 XT-PIC cascade 24: 883655 863043 IO-APIC-level ips 26: 7 9 IO-APIC-level aic7xxx 27: 8 8 IO-APIC-level aic7xxx 28: 97880608 96542591 IO-APIC-level eth0 NMI: 0 0 LOC: 52456889 52456887 ERR: 0 MIS: 0
procps version is 2.0.7 (Debian 3.0).
Where's the mistake -- should timer interrupts be on both CPUs (I think this is the problem), or is procps miscalculating Hz (seems less likely, someone would have noticed by now...)?
David.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |