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0 Replies Latest reply: Apr 22, 2013 1:52 PM by 1004735 RSS

Sun Grid Engine accounting file stats for jobs: cpu vs. ru_wallclock

1004735 Newbie
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These are the definitions of these job stats that I have:

cpu - The cpu time usage in seconds.

ru_wallclock - Difference between end_time and start_time.

For a 400 node SGE cluster, when I sum the times contained in cpu and ru_wallclock for
a month for all jobs, the totals are always close, but usually one aggregated stat exceeds the other.
There are cases where the sum of all ru_wallclock times for all jobs in a month exceeds the
sum of all cpu times for all jobs in a month (sometimes by roughly a thousand hours). But I had
thought such a scenario was impossible? Because According to wikipedia's explanation of CPU time:

"If a program uses parallel processing, total CPU time for that program would be more than its elapsed real time."

Also, would the total, theoretical upper bound for available ru_wallclock in a month for all nodes in a cluster be
total_number_of_nodes * 24 * 30 (days in a month)?

Is there any FAQ that discusses the statistics tracked in the SGE accounting file more in-depth?

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