Re: CPU wait time

Rick Denoire <100.17706_at_germanynet.de> wrote in message news:<95srvvsk8r65rhr9lenal3rsnc5l5ljl0s_at_4ax.com>...
> Using the "Performance Manager" delivered with the Tuning Pack of the
> OEM Software, I have noticed that CPU wait time is continuously shown
> as 97-98% ("CPU Overview" menu). At the operating system level, CPU
> usage is shown at about 60-80% at the same time. Perhaps the mismatch
> can be explained because Oracle only considers CPU time spent by
> Oracle itself.

I don't have any Solaris systems, so I won't comment here.

> Perhaps the CPU is "spinning" and actively polling for some resource
> to get free, which means that it is being wasted (assuming that other
> processes could benefit from an idle CPU). This is Oracle 9.2.0.4 on
> Solaris 7.
>
> I can't remember any "CPU wait time" in the statspack report.
>
> Should I try to tune the spinning behaviour to free CPU power?
>
> Bye
> Rick Denoire

Rick,

the event "CPU wait time" is new to 9.2.

Its good news, in terms of you're not bottlenecked on file IO (physical IO).
You want the system to be CPU bound, as the Oracle Server license and the CPUs tend to be the most expensive part of the system. If you're bound on network IO or on disk IO, either the code should be tuned to reduce utilization of those resources, or more resources should be allocated to those subsystems.

Its bad news, in terms of I'll bet that you have queries that are performing excessive logical IOs, hence being CPU bound, and not in a good way.
Do you also have a really high buffer cache hit ratio?

What do statspack reports from similar time intervals say? Examine the report for statements that produce a very high number of buffer gets per execution.

Pd Received on Fri Jan 09 2004 - 11:12:02 CST