RE: *Measuring sql performance (elapsed time and scalability) by number of logical reads
- From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
- To: "Dimitar Radoulov" <cichomitiko@xxxxxxxxx>
- Date: Wed, 3 May 2006 10:06:37 -0500
I agree. And that's what we get on the PARSE, EXEC, FETCH, UNMAP, SORT
UNMAP, and STAT lines. It's not presented in a lot of detail, but it's a
tradeoff between detail and measurement intrusion.
There's certainly more detail available; for example, events 10104,
10200, etc., but the measurement intrusion is significantly greater for
some of those events than it is for 10046.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Nullius in verba
Hotsos Symposium 2007 / March 4-8 / Dallas
Visit www.hotsos.com for curriculum and schedule details...
-----Original Message-----
From: Dimitar Radoulov [mailto:cichomitiko@xxxxxxxxx]
Sent: Tuesday, May 02, 2006 4:51 PM
To: Cary Millsap
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: *Measuring sql performance (elapsed time and scalability)
by number of logical reads
On 5/2/06, Cary Millsap <cary.millsap@xxxxxxxxxx> wrote:
> In the trace data context, those things listed below (hash value
> calculation, memory management, traversing hash chains, etc.) will
show
> up as time in the c field. ...Not as time in a "wait" event.
>
> I don't think the categorization "service" vs. "wait" helps people's
> thinking very much.
> A better way to think of the time being spent from
> Oracle's perspective is "kernel code path" vs. "OS call code path".
> Roughly speaking, the c field on a dbcall maps to kernel code path
> execution, and the ela field on so-called "wait" lines maps to OS call
> code path execution.
I think that instrumenting oracle kernel code path is as useful as OS
call code path instrumenting is.
> Notice that an OS call duration includes both waiting and service
time.
> This is the reason I don't like to use the word "wait interface".
>
>
> Cary Millsap
> Hotsos Enterprises, Ltd.
> http://www.hotsos.com
> Nullius in verba
>
> Hotsos Symposium 2007 / March 4-8 / Dallas
> Visit www.hotsos.com for curriculum and schedule details...
Regards,
Dimitre
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