RE: Performance Problem.
- From: Tanel Poder <tanel.poder.003@xxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 06 Nov 2007 23:20:04 +0800
> Now lets go to the cool sides of real Unixes. :) In Solaris
> 9, you can see what is TLB misses overhead using "trapstat
> -T". It will show % of time lost due to TLB miss. Works on
> SPARC but I'm not sure it will work on x86 as well.
Trapstat is not implemented on x86. But you can use prstat -m and look at
the TRP, TFL and DFL columns for trap, text page fault (executable) and data
page fault times for a process (or thread with -L option).
Regarding original posters observation that semaphore operations did
increase during the slowdown - this *may* be a symptom of a jump in latch
contention (as contending processes need to go to sleep and then be woken up
etc). This could be caused purely due the workload (inefficient query being
executed or CPU heavily overloaded) or it could be due something happening
at low-level in Oracle. Shared pool fragmentation and large allocations come
to mind first, but this could be anything else, and we can't be sure given
that we don't have any data to work on.
--
Regards,
Tanel Poder
http://blog.tanelpoder.com
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