Comment 0 for bug 859311

There seems to be a problem with the calculation of cpu-time for long-running multi-threaded processes. On a 2-way Xeon X5660 system, ps reports a cpu-time of 1184018577 days for a process that has been running for 5 days with 11 threads:

ps -f -C ustacks
UID PID PPID C STIME TTY TIME CMD
cul07b 13246 10866 99 Sep21 pts/0 1184018577-00:27:06 /home/cul07b/stacks/bin/ustacks -t fasta -f BN_pair1_mod.fasta -o ../results -i 2 -d -r -m 5 -M 2 -p 11

The corresponding /proc/13246/stat file looks like this:
13246 (ustacks) R 10866 10866 10861 34816 10866 4202496 2989827 0 0 0 85771819844 4611685996976182811 0 0 20 0 11 0 9806481 12440649728 2894242 18446744073709551615 1 1 0 0 0 0 0 0 0 18446744073709551615 0 0 17 3 0 0 0 0 0

top reports the same process with 0% cpu load although it is still running full-throttle with 11 threads:
13246 cul07b 20 0 11.6g 11g 1412 R 0 23.4 178668,22 ustacks

I saw similar issues with a process running for a couple of days with 48 threads on a 4-way AMD Opteron 6172 system.

I think the same bug has already reported on bugs.debian.org: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=641905

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: procps 1:3.2.8-1ubuntu4
ProcVersionSignature: Ubuntu 2.6.32-32.62-server 2.6.32.38+drm33.16
Uname: Linux 2.6.32-32-server x86_64
Architecture: amd64
Date: Mon Sep 26 11:32:31 2011
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=en_AU.UTF-8
SourcePackage: procps