RE: Timestamps in trace files

I don't know what the triggering event is for the kernel to "decide" when to emit a timestamp line to its trace data. But I have found that the frequency is nicely convenient for adjusting for clock drift. You could set up an experiment to figure it out as follows:

        Make a program that executes LIOs for 1 second between wait events, then 2 seconds between wait events, then 3, and so on. I'd bet that by the time you the program generated 30 seconds of LIO load between wait events, you'd have figured out how long of a delay causes the timestamp trigger.

By the way, you can make Oracle write a timestamp line to the trace file anytime you want by executing sys.dbms_system.ksdddt. I learned this little parcel of knowledge from Julian Dyke.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

Upcoming events:

- Hotsos Clinic 101 in Washington, Denver, Sydney
- Hotsos Symposium 2004, March 7-10 Dallas
- Visit www.hotsos.com for schedule details...

-----Original Message-----
From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com] On Behalf Of Gudmundur Josepsson
Sent: Wednesday, July 23, 2003 4:10 PM
To: Multiple recipients of list ORACLE-L Subject: Re: Timestamps in trace files

In the draft of Cary Millsap's upcoming book. You get a copy of it when you attend the Hotsos Clinic 101. Cary's supposed to be in DC right now teaching this course so I suggest he better make damn sure that he explains this properly (both there and on ORACLE-L :)

Gudmundur

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, July 23, 2003 3:04 PM

Gudmundur,
Where is this documented (so I can RTFM)? The one piece of this I don't quite understand is that the timestamp is not emitted twice in a row. If the long time is the triggering event, why do I see a gap of 90 minutes (in another trace file)?

Daniel

Gudmundur Bjarni Josepsson wrote:
>
> Daniel,
>
> Perhaps someone else can explain this better but the documentation I've
> got on this says that the Oracle kernel emits timestamps when a long
> time has elapsed since the last line was emitted to the trace file.
> Long time is defined as tens of seconds.
>
> Gudmundur
>
> > -----Original Message-----
> > From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com] On
> > Behalf Of Daniel Fink
> > Sent: 22. júlí 2003 21:19
> > To: Multiple recipients of list ORACLE-L
> > Subject: Timestamps in trace files
> >
> >
> > I was perusing a 10046 trace file and I noticed that
> > timestamps are written to the trace file. Sometimes they were
> > very regular (3 minutes apart give or take 30 seconds) while
> > other times they were hours apart. I have noticed that two
> > timestamps are never written without any intervening
> > activity. Anyone have any idea on the reasoning behind the
> > timestamps and the 'triggering event'?
> >
> > Daniel
> >
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Gudmundur Bjarni Josepsson
> INET: gbj_at_index.is
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Gudmundur Josepsson
  INET: gbj_at_index.is

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