Re: Awr waits over 100%
- From: Marcus Mönnig <mm@xxxxxxxxxxxxxxxx>
- To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 28 Sep 2011 17:41:49 +0200
Another shot with a short answer, instead of just a link: While your
client session/process waits for "log file sync" when comitting, the
LGWR process does the work of writing out the log buffer to disk and
waits for "log file parallel write". "log file parallel write" wait
events happen during the "log file sync" wait event.
Cheers,
Marcus
2011/9/28 Marcus Mönnig <mm@xxxxxxxxxxxxxxxx>:
> Hi Kenneth,
>
> the time for log buffer space and log file parallel write might partly
> be included in log file sync, especially when there are frequent
> commits, so there is some double counting taking place.
>
> Tony Hasler explained this in his 3 blog posts here:
> http://tonyhasler.wordpress.com/2011/07/24/log-file-sync-and-log-file-parallel-write-part-1/
>
> Cheers,
> Marcus
>
> 2011/9/28 Kenneth Naim <kennethnaim@xxxxxxxxx>:
>> I pulled an awr this morning for a period and the top wait events add up to
>> almost 200%. I was curious if anyone saw this before. I've seen it slightly
>> over 100% that I wrote off for rounding but never saw it so high. I'm
>> addressing the actual wait events so no issues there.
>>
>>
>>
>>
>>
>>
>> Top 5 Timed Events
>>
>>
>> Event
>>
>> Waits
>>
>> Time(s)
>>
>> Avg Wait(ms)
>>
>> % Total Call Time
>>
>> Wait Class
>>
>>
>> log file sync
>>
>> 356,514
>>
>> 2,521
>>
>> 7
>>
>> 84.5
>>
>> Commit
>>
>>
>> log file parallel write
>>
>> 358,641
>>
>> 1,967
>>
>> 5
>>
>> 65.9
>>
>> System I/O
>>
>>
>> CPU time
>>
>>
>>
>> 1,192
>>
>>
>>
>> 39.9
>>
>>
>>
>>
>> db file parallel write
>>
>> 23,911
>>
>> 364
>>
>> 15
>>
>> 12.2
>>
>> System I/O
>>
>>
>> log buffer space
>>
>> 135
>>
>> 58
>>
>> 427
>>
>> 1.9
>>
>> Configuration
>>
>>
>>
>> Thanks,
>>
>> ken
>>
>>
>>
>> --
>> //www.freelists.org/webpage/oracle-l
>>
>>
>>
>
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