# Re: Queueing Theory in Oracle

Date: Tue, 11 Mar 2014 10:51:23 -0500

Message-ID: <CACNsJnfZ7m630XfcSmoXa7h6zeU3rAADJ2b9m9Me47bc-qNjKA_at_mail.gmail.com>

I've read both of the books, and I love them. On this link are my notes - http://goo.gl/b8aNOj

Although queueing theory is pretty cool, I find the chapter on regression analysis more suited for real world but the queueing theory chapter builds a nice foundation of ResponseTime=ServiceTime+QueueTime which is from a practical use case point of view the Performance Page you've got all of that components in a nice pretty dashboard broken down into wait class with CPU as your service time and everything else is QueueTime.

For the regression analysis on the link (r2project), what I did is rank the independent values (x) that has the high correlation coefficient and make use of that to forecast the dependent value (y). Also the page 8 of this paper http://www.slideshare.net/karlarao/where-didmycpugo also gives you more insights about the "more CPUs, faster CPUs, more and faster CPUs" section of the book, I think it's page 32.

-Karl

On Tue, Mar 11, 2014 at 9:46 AM, Ls Cheng <exriscer_at_gmail.com> wrote:

*> Hi*

*>*

*> I have been reading Craig's book and Cary's book (chapter 9) for the last*

*> 2 weeks, the theory in the books look great but when I tried to start using*

*> in the real world it the questions started to appear.*

*>*

*> For example, arrival rate, what arrival rate in Oracle is exponentially*

*> distributed......? Cary says logical reads in his book but I just dont see*

*> how can that be possible by using the database metric (for example system*

*> metric such as Logical Reads Per Sec or Logical Reads Per User Call).*

*> Craig's book I dont even mention a useful database metric (I havent*

*> finished the book yet so I might have missed if he has said so), the book*

*> just uses all the time the work unit transaction per second.*

*>*

*> Both book provide a queueing theory workbook but they are useless from*

*> database metric point of view since no metric is poisson or exponential*

*> distributed (again I am not able to see it, if someone can please advice).*

*>*

*> But Jonathan you just mention "buffer gets per user call" which is similar*

*> to Logical Reads Per User Call from v$sysmetric, why do you think that is*

*> exponentially distributed :-?*

*>*

*>*

*> Thanks*

*>*

*>*

*>*

*>*

*> On Tue, Mar 11, 2014 at 3:30 PM, Jonathan Lewis <*

*> jonathan_at_jlcomp.demon.co.uk> wrote:*

*>*

*>>*

*>> It's an interesting question - and I don't think you can find a current*

*>> metric that would help unless you started doing something a little clever*

*>> with ASH.*

*>>*

*>> In an OLTP system something like 'buffer gets per user call" would*

*>> probably be a reasonable fit - but there's no capture at that granularity.*

*>> Similarly disc I/O requests per call might be appropriate. Then there are*

*>> things like disk I/O requests per disc per second. But every possibility I*

*>> think of requires too fine a level of granularity unless you can find a way*

*>> to construct a valid model from the samples in v$active_session_history.*

*>>*

*>>*

*>>*

*>> Regards*

*>> Jonathan Lewis*

*>> http://jonathanlewis.wordpress.com*

*>> _at_jloracle*

*>> ------------------------------*

*>> *From:* oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] on*

*>> behalf of Ls Cheng [exriscer_at_gmail.com]*

*>> *Sent:* 11 March 2014 14:20*

*>> *To:* Paul Houghton*

*>> *Cc:* Oracle Mailinglist*

*>> *Subject:* Re: Queueing Theory in Oracle*

*>>*

*>> Hi*

*>>*

*>> I have had a quick read, I think the link you posted talks about queue*

*>> time but not about queueing theory such as a M/M/n model. The problem is I*

*>> am not able to find a database metric that is exponential distributed which*

*>> allows us to use the M/M/n queueing theory.*

*>>*

*>> Thanks*

*>>*

*>>*

*>>*

*>> On Tue, Mar 11, 2014 at 3:16 PM, Paul Houghton <*

*>> Paul.Houghton_at_admin.cam.ac.uk> wrote:*

*>>*

*>>> Craig Shallahamer talks about queuing theory in the following blog post.*

*>>>*

*>>>*

*>>> http://shallahamer-orapub.blogspot.co.uk/2011/08/why-tuning-oracle-works-and-modeling-it.html*

*>>>*

*>>> I hope this is helpful*

*>>>*

*>>> PaulH*

*>>>*

*>>>*

*>>*

*>*

-- Karl Arao Blog: karlarao.wordpress.com Wiki: karlarao.tiddlyspot.com Twitter: _at_karlarao <http://twitter.com/karlarao> -- http://www.freelists.org/webpage/oracle-lReceived on Tue Mar 11 2014 - 16:51:23 CET