Load on 2 CPUs is smaller than 2 times load on 1 CPU, how to improve?

Question

Good afternoon,
I am trying to improve the performance on my system.
I have used "pbind" to fix a process on a CPU, like this:
Process P1 -> CPU 1
Process P2 -> CPU 2
Every process uses Oracle access (although most of the data are loaded into memory) and a connection towards another central process.
The problem now is the following:
if I launch process P1 50 times/second, the first CPU runs on 22% idle.
If I launch, next to P1, process P2 also 50 times/second, both CPUs (1 and 2) run on 19-20% idle.
If I launch, next to P1 and P2, process P3 also 50 times/second, all three CPUs (1, 2 and 3) run on 16-17% idle.
As my systems contains 16 CPUs, at the end, I loose 56% performance.
Now I wonder what is the nature of this performance killer? Is it simultaneous disk access, simulateneous interprocess communication, is it a purely UNIX related issue, is it an Oracle problem, ...?
Can anybody give me some ideas which could be the problems and how to investigate how to detect and verify them?
Thanks
Dominique

Answer 1

Try this, almost identical, but with less execution time.
SELECT
a.Consumption AS Consumption ,
a.Cost AS Cost ,
a.CreatedBy AS CreatedBy ,
a.CreatedDate AS CreatedDate ,
a.UpdatedBy AS UpdatedBy ,
a.UpdatedDate AS UpdatedDate
FROM Positions b
JOIN PortConsumption a
ON a.PortRotationId = b.Id
WHERE b.VoyageId ='82A042031E1B4C38A9832A6678A695A4';Rgds,
Ahmer