xcode_process_num_threads Value?

[joe123]

I have a dual core Intel system and I recently upgraded from 6.4 to 6.5.9. Transcoder.exe is now using more more than one CPU as per the new threads option in 6.5.

The documentation says that if the value of xcode_process_num_threads is left at zero, it will use one thread per CPU plus 1, so a total of 3 in my case since I have 2 CPUs.

I been playing with various values for the threads and they don't add up. For example:

When:

xcode_process_num_threads=0, I get around ~60% total CPU utilization.
xcode_process_num_threads=4, I get around ~70% total CPU utilization.
xcode_process_num_threads=6, I get around ~80% total CPU utilization.

My XP process viewer shows each increment that it is processing the file faster by the amount of disk I/O from Transcoder.exe, so I know that increasing xcode_process_num_threads is NOT over subscribing my CPUs and thus running slower overall.

So my question is how does this value actually map out? I thought 2 threads for me was ideal since I have 2 CPUs, but at 2, the CPUs are never at 100% utilization.

Anyone else played with this?