IDS Forum

Re: CPUVP overloaded but physical CPU only 50% used

Posted By: Madison Pruet
Date: Wednesday, 9 July 2003, at 5:26 p.m.

In Response To: CPUVP overloaded but physical CPU only 50% used (geoff.poole@verizon.com)

We need to look at other things besides cpu utilization to address
performance issues. Have you checked to see if the ready queues have
anything on them? If the threads are waiting on some non-cpu resource,
then having excess cpu power is not going to help. If the contention
resource is cpu power, then I would expect to see threads always in the
ready queue (onstat -g rea). If you don't see threads there, then I'd
search other resources to see where the contention really is.

M.Pruet





"geoff.poole...."
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Sent by: Subject: CPUVP overloaded but physical CPU only 50% used [1524]
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07/09/2003 02:40
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Has anyone set NUMCPUVP to be more than the number of physical CPUs ? and
has anyone seen similar problems.

We have a problem that our informix instance gets overloaded (30+ active
queries for minutes) with user complaining of timed out jobs, but our total
CPU's utilization (sar) stays below 50% and I note that we have lots of
ready threads. I've set NUMCPUS to 7 which is text book -1 the number of
physical CPUs (8).

Could it be that in the new super-fast CPU clock speeds that the engine's
internal architecture needs to be rethought, perhaps threads are yielding
too quickly and there is a problem with the mechanism of thread context
switching ?

Versions: 9.30.FC2R1 AIX 5.1
System Model: IBM,7040-681
Memory Size: 32768 MB
Number Of Processors: 8
Processor Clock Speed: 1300 MHz
CPU Type: 64-bit

Geoff Poole
Verizon Florida

Messages In This Thread

• CPUVP overloaded but physical CPU only 50% used
  geoff.poole@verizon.com -- Wednesday, 9 July 2003, at 3:40 p.m.
  • RE: CPUVP overloaded but physical CPU only 50% used
    Jay Aymond -- Wednesday, 9 July 2003, at 4:29 p.m.
  • Re: CPUVP overloaded but physical CPU only 50% used
    Madison Pruet -- Wednesday, 9 July 2003, at 5:26 p.m.
    • Re: CPUVP overloaded but physical CPU only 50% used
      Mark Scranton -- Wednesday, 9 July 2003, at 8:06 p.m.
  • Re: CPUVP overloaded but physical CPU only 50% used
    Michael Mueller -- Thursday, 10 July 2003, at 7:40 a.m.
  • CPUVP overloaded but physical CPU only 50% used
    Gregory S. Williamson -- Thursday, 10 July 2003, at 5:41 p.m.

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