Oracle export process eating up 95-99% of server cpu

Question

Hi Everyone,
I noticed that my export process is eating a huge amount of the server's cpu resources.
Is there a way to control the resources allocated to my export process?
thanks

Answer 1

>Isn't that spinning and CPU usage ?
Yes. No. Spinning on a latch means that the process is in wait state - waiting to access the resource. It means that every now and then, the process will check the resource state to determine if it can obtain access to it.
Does "spinning" eat up CPU time? Typically not. And 99% of the time where is does, it is due to the type of shoddy "loop spinning" that I've demonstrated with the 1st sample piece of code above (called [url http://en.wikipedia.org/wiki/Busy_waiting]busy waiting).
The norm is that a process in a wait state consumes very little CPU time. There are actual CPU instructions that tells the CPU to "ease off", like the [url http://en.wikipedia.org/wiki/HLT]HLT instruction. This instruction is used at a higher level abstract(API) level - like with the DBMS_LOCK.SLEEP() API call.
> CPU usage DOES convey information.
You are missing the basic point that I was trying to make. In terms of performance measurement, it says nothing. It does not say GOOD. It does not say BAD.
Why?
An idle CPU can be a result of exceedingly poor performance caused by process serialisation (like in PL/SQL doing your own sequences by locking a table to do a SELECT MAX() to get next sequence number to use). Seen this one myself and most recently on a Superdome that showed idle CPU utilisation with the performance being excruciatingly slow.
An idle CPU can be simply because of no work to be done.
An idle CPU could be because of an I/O bottleneck as a 200 parallel query processes all hit the same I/O channels.. and then have to sit back and wait for the I/O calls to be completed. Saw this one often on Oracle Parallel Server (OPS) many years ago.
Similar situation for a heavily utilised CPU. The actual utilisation figure does not tell you how much of that CPU time used, is used effectively by optimally designed and coded processes.. and how must is wasted by poorly design and coded processes.
From a performance perspective, it alone says nothing.
And this is what the OP says - he's seeing 95+% CPU utilisation when running an export. Is it a performance problem? If so, what can he do about it?
The answer to which is, identify if there is an actual performance problem as 95% CPU utilisation alone does not tell us whether that is good and efficient usage of CPU time, or abuse and wasted use of CPU time.