Software suggestion:

[axn]

BTW, the correct setting for P-1 to work on two threads is:

WorkerThreads=1
ThreadsPerTest=2

[James Heinrich]

Jumping late into this thread: it looks to me like dominicanpapi82 very likely has a hyperthreaded, single-core P4-3.2Hz. The apparent "second core" that Windows shows is not really there, it is very very different from the first, physical core. Hyperthreaded CPUs can give a performance boost typically around +10-15% over the non-hyperthreaded single-core, but results vary greatly depending on what the workload is (it could be +30%, it could actually be slower than single-core in some cases). There's plenty of threads on the forum about hyperthreaded performance; you'll probable find some testing results and optimal configurations in there. In the posted screenshot, the system was 42% idle over the doubled cores, which means that useful work is occupying 58/50=116% of the capacity of the non-hyperthreaded singlecore, which looks just about expected. Even if you do get the CPU utilization up to show close to 100%, your throughput is not going to be hugely better (doing simultaneous P-1 and TF will have slightly higher throughput than P-1 alone, but it also means that the P-1 will take nearly twice as long (maybe 1.85x?) to complete compared to it running by itself).

[lfm]

Originally Posted by James Heinrich

Jumping late into this thread: it looks to me like dominicanpapi82 very likely has a hyperthreaded, single-core P4-3.2Hz. The apparent "second core" that Windows shows is not really there, it is very very different from the first, physical core. Hyperthreaded CPUs can give a performance boost typically around +10-15% over the non-hyperthreaded single-core, but results vary greatly depending on what the workload is (it could be +30%, it could actually be slower than single-core in some cases). There's plenty of threads on the forum about hyperthreaded performance; you'll probable find some testing results and optimal configurations in there. In the posted screenshot, the system was 42% idle over the doubled cores, which means that useful work is occupying 58/50=116% of the capacity of the non-hyperthreaded singlecore, which looks just about expected. Even if you do get the CPU utilization up to show close to 100%, your throughput is not going to be hugely better (doing simultaneous P-1 and TF will have slightly higher throughput than P-1 alone, but it also means that the P-1 will take nearly twice as long (maybe 1.85x?) to complete compared to it running by itself).

But wouldn't the OS report both CPUs as active rather than showing 42% idle even tho they were producing less total work results than they might? The idle task will only report time when a CPU finds no other task runnable. It will not and cannot report idleness within instructions due to functional unit conflicts between hyperthreaded CPUs any more than it can report waits for cache misses to go to main memory.

For the idle task to get control and start measuring time you need a task wait such as a page file wait or an intertask lock wait.

Perhaps dominicanpapi82 could tell us exactly what model CPU he has?

[xorbe]

P-1 is definitely chewing up almost all of 8 threads here (25.8b4 64-bit, Windows)