Hi all.

I have a doubt.. when you have a server with multi CPU and cores. does the OS assign them or is the application who should be able to use them?

I have a red hat server with several cpu/cores and oracle seems to be using 1 core.. instead of using all of them..

not sure if it is something that have to be change on the OS or in the oracle DB application.

any idea where should I start looking at?


Edit:
when I run top. and press 1 I see all the cores, some few has a of use but looks like randomly there is always 1 in 100% or maybe 2 in 49% and 50%..

then on the process list there is oracle always in 100% or 99%..while the overall id% is 94%...

I would like to verify is the application or CPUs core are being used properly.
thanks

First the application may or may not be divided into multiple threads. Many applications are not divided into multiple threads. It is trickier to code an application for multiple threads than for single thread. If the application is single thread, there is nothing the OS can do to make the application get better use of multiple cores.

I don't use any Oracle DB, so I find it surprising that a limit to single thread would exist in that application. But I don't really know.

If the application is multi-threaded and the application does not go to significant extra effort to mange/limit its use of physical cores, then it is the OS that assigns threads to cores. But for purposes of your question, I find it highly unlikely that some OS flaw or weird setting is responsible for the unexpected behavior you report.

Agreed - locking is another consideration.
Merely making an application multi-threaded doesn't make it is thread safe. But you've have to think Oracle has all that sorted out by now - sounds like a (user) config issue.

Yes, if I remember well that is only a configuration issue (of oracle db server). But probably it has changed since then.

Well, I have been playing with ps- eLF, htop, etc...

I see activity on all of the cores.. only one process is using one core at the time 100...it could be any core from 1 to 16 ....

there are SEVERAL Oracle processes running across different cores.. so looks like from a OS perspective is fine and there is not a limitation.. even in oracle seems to be recognizing mutliple cores..

the problem is with ONE particular process.

I'm not a DBA, not have access to the oracle DB. so I would check with the DBA to see if they know something..

looks like oracle have something called "Parallel SQL Execution".. will continue reading about it too..

If linux kernel feature process affinity is set to use one core for all threads of single app then it may do like this.

This isn't a licensing thing is it? Some Software and hardware vendors can charge a licence fee per core so you only get what you pay for. I know that IBM and HP do this for some of their higher end products (usually not X86 based CPUs) Does Oracle charge a fee to allow scaling of its software in a similar way?

Just a thought...

Play Bonny!

A single application (process) will run on only one core at a time, unless it is a multi-threaded process.

However, you should ordinarily observe that process being dispatched at-random among the various available cores . . .