I guess where I'm getting confused - sort of - is this is what my boinc manager looks like. I understand the hyperthreading is just cramming more stuff into the same pipe.




Thanks,
William

William, your system is working normally.

It's only the Kepler GPU's that are at optimal if they are using a full CPU core, and this was only apparent for the NATHAN_dhfr36_ WU's. It actually suggests that Noelia's work units might benefit from having more CPU access, but that's a different issue.

Your GTX560Ti is a Fermi (not a Kepler). It's Compute Capable 2.1 (while Kepler's are CC3.0, and Titan is CC3.5). The Fermi GPU's don't use as much CPU because they are doing some calculations on the GPU that the Kepler cannot perform on the GPU (different architectures). So the Kepler's use more CPU (well, that's my simplified interpretation). The theory is that if the Keplers are competing for CPU access it will slow down the WU. This was demonstrated to be the case to some extent for both NATHAN's and Noelia's WU's. Basically if you use too much CPU crunching CPU tasks for other projects it will slow the work down here (again only for the Kepler GPU's, and not your Fermi).

Your "0.571 CPU's" is just an estimate, and is usually inaccurate. My "estimate" is ~0.687 for both Nathan's and Noelia's WU's on both my Kepler and Fermi, however the Kepler actually uses 100% of a CPU for Nate's work and 44% for Noelia's work, and my Fermi uses ~12.5% for Nate's work units and and between 5 and 10% for Noelia work.

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skgiven et al.

Thanks for the explanations!

William

skgiven, thanks for the advice. I didn't realize this as the tasks report using 0.721 cores each and together the two 680s would only remove 1 of my cores from crunching CPU tasks (I knew the math didn't make sense). I've now lowered my CPU usage. Hopefully this will improve my contributions. Looking into other sources of slowdown as well.

This may be a silly question, but in BOINC preferences, do I need to set the number of processors used to a certain ratio of the total processors? For example, if I set it to 75% of my 8 cores, that will enable 6 cores. If I set it to 62.5% that will enable 5 of 8 cores. If I were to set it to 70%, this would be 5.6 cores. Is this possible? How does this work, or should I stick to percentages that give whole numbers of cores?

It can't do fractions of a core/thread. So 75% up to 86% is still 6/8 threads. 87.5% is 7/8 threads, as is 89% and 94% and 99%. 100% is all CPU threads, 8/8.

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Alright, that's what I thought. Just wanted to make sure I wasn't missing something. Thank you.