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Home -> Community -> Mailing Lists -> Oracle-L -> RE: CPU WAIT I/O statistic
Pablo - I posted the following paragraph yesterday:
3) I looked in Oracle Performance Tuning 101 to see what Gaja has to say. He points out that the Solaris sar -q command has a "%wio" column, a measure of processes that are currently using the CPU, but are waiting for I/O requests to be serviced and hence are not making prudent use of the CPU. He further says that %sys and %wio should be less than 10-15% and if it is consistently higher you need to get to the bottom of it, and usually it is a application causing the problem. No details on how to get to the bottom.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Thursday, October 10, 2002 3:16 PM
To: Multiple recipients of list ORACLE-L
Hi list
Can anyone explain me what exactly does the WAIT I/O column of the sar -u output mean?
Does it represent the % of CPU used by the kernel processes to perform I/O?
As far as I know the waiting processes do no wait actively when they ask for an I/O. right? The OS uses the SLEEP and WAKEUP primitives.
So, Which process is using this CPU? (The WAIT I/O%)
Or does this WAIT I/O have to be taken as if the CPU were idle?
Please shed some light on this.
Thanks
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Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services ---------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Thu Oct 10 2002 - 15:28:39 CDT
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