---559023410-851401618-1009933243=:7513
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hello,
we are encountering some weird timing behaviour on our linux cluster.
specifically: when running 2 copies of selected programs on a
dual-cpu system, the cputime reported for each process is up to 25%
higher than when the processes are run on their own. however, if running
two different jobs on the same machine, both complete with a cputime
equal to when run individually. sample timing output attached.
profiling confirms that everything slows down approximately to scale.
the results reproduce on a range of different machines (see below).
additional specifications:
- kernel version 2.4.16 (with apic enabled)
- chipsets: apollo pro 133, apollo pro 266,
intel i860, serverworks LE
- all jobs requires less than 1/10 of physical memory
- no significant disk i/o takes place
- timing with dtime(), /usr/bin/time and shell built-in time
- this behavior is NOT seen for all applications. the worst
"offender" spends most of its time doing linear algebra.
ideas or info-pointers appreciated. more specs available on request.
regards,
-- Steinar Hauan, dept of ChemE -- hauan@cmu.edu Carnegie Mellon University, Pittsburgh PA, USA---559023410-851401618-1009933243=:7513 Content-Type: TEXT/PLAIN; charset=US-ASCII; name="one.txt" Content-Transfer-Encoding: BASE64 Content-ID: <Pine.GSO.4.33L-022.0201012000430.7513@unix13.andrew.cmu.edu> Content-Description: Content-Disposition: attachment; filename="one.txt"
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