Bug#495529: linux-source: SMP process scheduler leaves CPUs idle

[Paul Szabo <psz@maths.usyd.edu.au>]

Package: linux-source
Version: 2.6.18.dfsg.1-18etch6
Severity: normal


I have some machines with 8 CPUs (dual Intel Xeon quad-core CPU chips),
used for long-running calculations; normally there are no short-lived
processes. If all processes are "niced" to the same or nearby level,
then things behave as expected. But if there is a large difference in
the "nice" level (e.g. one job at level 15 and 8 jobs at level 18), then
one CPU is left idle: total CPU percentages adding to 700% and "top"
shows idleness at 12.5%. (Under some similar conditions I have also
observed 2 idle CPUs.)

Please let me know if you need further details.

Thanks,

Paul Szabo   psz@maths.usyd.edu.au   http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics   University of Sydney    Australia


-- System Information:
Debian Release: 4.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-pk02.19-svr
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)