Process time accounting problem on two CPU machines. Resolved?

[Lew Randerson <LRanderson PPPL Gov>]

Around last October, Lars Hjorth reported a process time accounting problem to
axp-list. Was that resolved?

We are running kernel 2.2.16 on several UP2000 Dual Alpha machines and
are seeing the same problem. i.e. There is no reported cpu usage on the
second cpu even though we know it is being used. For each process,
/proc/<pid>/cpu always shows cpu1 with no time. /proc/cpuinfo does
show 2 active cpus. The machines were deliverd with 2.2.14 and had
the problem with that kernel also.


   # /usr/bin/uptime
   3:48pm up 31 min, 5 users, load average: 4.08, 3.30, 1.93

   # /bin/grep cpu /proc/stat /proc/{1209,1211}/cpu
   /proc/stat:cpu 656276 0 97507 3080381
   /proc/stat:cpu0 656276 0 97507 1163299
   /proc/stat:cpu1 0 0 0 1917082
   /proc/1209/cpu:cpu 112750 436
   /proc/1209/cpu:cpu0 112750 436
   /proc/1209/cpu:cpu1 0 0
   /proc/1211/cpu:cpu 104966 410
   /proc/1211/cpu:cpu0 104966 410
   /proc/1211/cpu:cpu1 0 0

Note in /proc/stat the idle time for cpu1 is essentially the same as the
system uptime. So cpu1 is reporting NO user time. My first pass at the
Linux source showed nothing glaringly wrong in kernel/sched.c or
alpha/kernel/smp.c..


Note: All utilities show CPU1 is not used including xosview and procinfo.
Reported CPU usage is accurate when the machine is booted with nosmp
and therefore only one cpu is active.

Thanks for any info, --Lew

Lew Randerson
Computational Plasma Physics Group
Princeton Plasma Physics Lab, Princeton University
P.O. Box 451
Princeton, NJ 08543

lranderson@pppl.gov
1 609 243-3134 (voice)
1 609 254-3086 (fax)