Re: Adding CPU to a unix box--added capacity.
- From: "Alex Gorbachev" <ag@xxxxxxxxxxxx>
- To: David.Best@xxxxxxxxxx
- Date: Sat, 3 Nov 2007 19:37:30 -0500
In addition to my previous reply and to what David shared, I can mention result of one project with our client where we did a benchmark of CPUs migrating from double core Santa Rosa to quad core Barcelona. Single core of Barcelona was slower (we had one of the first chips I think... something like 1.6 or 1.8 GHz). We calculated new and old capacity purely based on number of cores and GHz and we had 60% increase in capacity. We used TPC-C traffic and we did see increase of throughput on the same level. However, TPC-C transactions are very simplistic and usually far from real-life transactions. On Nov 3, 2007 7:14 PM, Best, David <David.Best@xxxxxxxxxx> wrote: > > > A while back we doubled the number of cpu's in a system from 2 to 4. I > monitored CPU usage at 5 minute intervals for the week before and the week > after. > > For the 4cpu week the average CPU usage was: 26.39815 > > For the 2cpu week the average CPU usage was: 54.78056 > > So, CPU usage pretty much halved which was what we expected. However, that > doesn't necessarily mean performance will increase by a factor of 2. It > depends on the application. In this case the databases on this server were > a mix of OLTP and Datamarts. The OLTP databases did see an improvement but > the datamarts didn't. The reason is that OLTP transactions are normally > short and sweet, so more could be processed at a given time. In the case > of the datamart, the refresh job didn't take advantage of multiple cpu's, so > it still took the same amount of time to complete. > > ________________________________ > > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] > On Behalf Of Zhu,Chao > Sent: Friday, November 02, 2007 10:32 AM > > To: oracle-l > Subject: Adding CPU to a unix box--added capacity. > > > > hi, > Does anyone have experience on adding new CPU to a existing box, like > upgrade from 8CPU to 16 CPU for example. > I am curious about two things; > 1. How many CPU usage% drop do we expect? Like previously it is running at > 50% CPU usage, typically will it drop to 25%? or something like 30%? To ask > the same question from another view, is , how much capacity we add to the > box? 16CPU box = 1.X(?) of a 8CPU box. Assuming same archtecture/OS. (same > cpu count server in different architecture may have different processing > power?) > Would be nice if you can share with your experience (like on > solaris/aix/hp etc). That's kind of typical server scalability. > > 2. Can we say, CPU_USED_BY_THIS_SESSION (stat in oracle) ~~ > Unix_CPU_COUNT * USER_MODE_CPU% (vmstat usr column)? I did couple of compare > in my database, they look pretty close. > > Does anyone ever thinking about have such a formular: it could be very > fun. > CPU_USED_BY_THIS_SESSION = X*logical_reads + Y*physical_reads + Z*sorts + A > * executions + B * redo_size + C * Latch_Spins+ .......? > > by the way, anyone like the book"forecasting oracle performance"? > -- > Regards > Zhu Chao > www.cnoug.org > -- Alex Gorbachev, Oracle DBA Brewer, The Pythian Group http://www.pythian.com/blogs/author/alex http://www.oracloid.com BAAG party - www.BattleAgainstAnyGuess.com -- http://www.freelists.org/webpage/oracle-l