The elapsed time to complete operations is almost the same in all 4 different CPUs

[Eric Fu]

Hi Sirs,

We conducted the command ./pt_linux_x64 -p 4 -i 16 -d 4 -r 1 and the elapsed time to complete operations is almost the same in all 4 different CPUs.

Core 7, the elapsed time is 51:06
Core 5, the elapsed time is 51:05
Core 3, the elapsed time is 51:08
Celeron, the elapsed time is 51:04

We also conducted the command ./pt_linux_x64 -p 24 -i 32 -d 4 -r 1 and the elapsed time to complete operations is also almost the same in all 4 different CPUs.

Core 7, the elapsed time is 116:34
Core 5, the elapsed time is 116:23
Core 3, the elapsed time is 117:05
Celeron, the elapsed time is 116:46

Can you help explain the results? I guess if we increase the process number to 1024, we should be able to see a significant difference. Please help explain the reason.

Thanks,
Eric Fu

[Richard (PassMark)]

We do not see an issue. The test will stop once the specified elapsed time for the test has elapsed. The "-d 4" specifies a Test Duration of Very Long (20 seconds). Each process will run simultaneously until at least 20 seconds has passed and return the number of operations performed in that time.

[David (PassMark)]

The amount of work done (number of operations completed) should be larger for the faster CPUs however.

[Eric Fu]

Yes, I agree. Do you think using a faster CPU should obtain a shorter elapsed time than using a slower CPU regarding running Passmark performance test in Linux?

Thanks,
Eric Fu

[David (PassMark)]

No.
If you ask it to run for 20 seconds, then it doesn't matter how fast the CPU is, the run time will not be under 20sec.
(there is some overhead like thread synchronization, etc.., which results in test times longer than 20sec if you ask for 20sec)

[Eric Fu]

Thank you!!!
I guess if the minimum required time for a single test thread to complete is within 20sec, then setting the 20sec duration can obtain the same elapsed time among CPUs.