Larry, See pages 170–173 if you have access to a copy of *Optimizing Oracle Performance *(O'Reilly). Bottom line: unaccounted-for time in trace data on Oracle 9.2 or beyond is almost certainly time spent preempted. Your analysis is sweet-spot for two of the software tools we make. Check out these if you're interested: - Method R Profiler (http://method-r.com/software/profiler), which reports on properly aggregated unaccounted-for time. - And *mrnl* (http://method-r.com/component/content/article/116) in the MR Tools suite, which allows you to drill in on exactly which specific * lines* of trace data are contributing the most unaccounted-for time. The final example on the *mrnl* web page I pointed to at the beginning of this paragraph is your situation on the nose. Let me know if there's anything we can do for you... Cary Millsap Method R Corporation http://method-r.com On Wed, Dec 2, 2009 at 2:13 PM, Larry G. Elkins <elkinsl@xxxxxxxxx> wrote: > Listers, > > SA's asking for assistance on how to tell if a process is being impacted > and > to what degree by processor pre-emption. AIX 5.3. Asked in the context of > trouble-shooting some significant unaccounted for time issues in 10046 > trace > files (e.g. 14 of 16 seconds unaccounted for vendor process, 300 of 700 > seconds unaccounted for vendor batch job, etc). SA's have "ruled out" > overhead of writing the trace file so now looking at the pre-emption > aspect. > A bit out of my league, and I find plenty of approaches in IBM docs, and > from people on this list (but geared more towards Solaris and other > flavors, > not Aix). 9.2.0.8 EE and 10.2.0.4 EE, "static" and dynamic LPAR's, seen on > various boxes and databases. > > Larry G. Elkins > > > -- > //www.freelists.org/webpage/oracle-l > > >