Re: The best CPU usage measurement in Oracle: BUFFER_GETS or CPU

From: Danisment Gazi Unal (ubTools) <dunal_at_ubTools.com>
Date: Fri, 18 Jun 2004 11:10:08 +0300
Message-ID: <04fa01c4550b$b2cff1b0$fe19100a@danismentgu>

Jurijs,

There are still many traps in Oracle response time measurements. You can see them at http://www.ubtools.com/cgi-bin/ib/ikonboard.cgi?act=Pages;page=mrpp

As a short glance, "don't ignore logial IO, but starts with CPU time".

I'm developing some new formulas for response time analysis. Some of them is related to measure impact of CPU power and logical IO on CPU time. I guess they will be available soon in itrprof.

best regards...

http://www.ubTools.com
Web Based Oracle Products and Services

Original Message ----- From: J.Velikanovs_at_alise.lv To: oracle-l_at_freelists.org Sent: Friday, June 18, 2004 10:47 AM Subject: The best CPU usage measurement in Oracle: BUFFER_GETS or CPU_TIME?

My regards to all members,
Just would like to know your opinion. Since 9i (suppose 9.2) we have CPU_TIME column in the V$SQL view.

I wonder which figure is the best measurement of CPU usage BUFFER_GETS or CPU_TIME?

Lets imagine I have system with CPU bottleneck (can see height “load average” from OS) for a 1-3 ours. No particular long sessions have been executed. It is seams mainly OLTP system. Parse CPU usage not the issue.

I would like to identify TOP CPU consumers. As we all know I the V$SQL is the best information source in this case.

I wonder which figure is the best measurement of CPU usage: BUFFER_GETS or CPU_TIME? Statspack report, as well as Anjo Kolk www.oraperf.com recommending to look on BUFFER_GETS not to CPU_TIME. Is it just tradition or there are some arguments not to look on CPU_TIME as main CPU usage indicator.

One reason I can imagine why CPU_TIME better indicator then BUFFER_GETS is sorting. I can imagine that BUFFER_GETS not taking in account CPU spent to sorting staff. Then from CPU usage perspective better indicator is CPU_TIME. Please correct me if I am wrong.

Thanks in advance,
Jurijs

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Received on Fri Jun 18 2004 - 03:06:24 CDT

Re: The best CPU usage measurement in Oracle: BUFFER_GETS or CPU_TIME?