How to speed up calculation on a multi-core PC

[Kelly_E_]

We use a PC operated by Window 7. It has 1 physical processor, 4 cores, 4 logical processors. The Exe was for calcuation only with no visual application and was compiled by Intel Fortran 2012 XE

When running one job, it took 78 seconds to finish.

When running two same jobs at the same time, it took 98 seconds to finish for each job.

When running three same jobs at the same time, it took 223 seconds to finish for each job.

The set up of Affinity in Task Manager did help to speed up calculation.

Do you know why the calculation was slow when 3+ jobs are running at the same time?

[Kevin_D_Intel]

Your question is better asked in the Intel® Visual Fortran Compiler for Windows* forum. I will inquire if your post can be moved to that forum for you.

[Steven_L_Intel1]

How much memory do these jobs use? Any I/O? It might be interesting to watch the system memory statistics while the jobs are running. My guess is that they are exhausting memory and are page-faulting.

[gqxsun]

Hi Steve, The PC has 4G ram. In compling option: linker>system>stack reserve size = 300Mb In compling option: linker>system>stack commit size = 300Mb when testing the speed, there was no other programm running. Thank you for the help

[gqxsun]

Hi Steve, Add more info: Heap reserve size = 0 Heap commit size = 0 were used in compiling. 3 jobs mentioned in my previous e-mail were submitted to run from 3 separate working directories by DOS commends.

[Steven_L_Intel1]

That doesn't really tell me anything. You have to run the Task Manager or Resource Monitor to see how much CPU utilization is and how the memory is being used. I assume you have large arrays - how big in total? How much RAM on this system? As I noted earlier, the slowdowns you are seeing are a sign of contention for some resource, most often RAM.