Hi All,
We're trying to work out why mpstat and "ps -opcpu" gives some very
different results. The server we're looking at is a zone, when we do
something like "ps -ef -o pcpu | awk '{t+=$1} END {print t}'" and
compare it to "mpstat 1", they're very different. Here is one sample
output.
# ps -ef -o pcpu | awk '{t+=$1} END {print t}'
10.2
# mpstat 2
CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl
0 6566 0 1958 427 43 1650 310 197 98 0 17080 40 43
0 16
1 7424 0 1718 1669 1337 1784 356 197 112 0 15446 44 43
0 14
Output from ps is saying 10% of CPU is used, whereas mpstat is saying
15% CPU are idle. The figures are almost the inverse of each other.
This is done on two seperate terminals at the same time. The man page of
ps on pcpu says:
The ratio of CPU time used recently to CPU time available in the
same period, expressed as a percentage. The meaning of ``recently''
in this context is unspecified. The CPU time available is
determined in an unspecified manner.
Does that mean pcpu is just some random numbers?!
I had a quick look at the code in ps.c, looks like it's getting it from
/proc into struct psinfo, but how are the values in psinfo calculated?
Is mpstat zone aware or is it just reporting the stats from the global
zone?
Any pointers?
Thanks,
Andrew
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