Installed BOINC and joined climateprediction.net today. Two models began running and my preferences include using both CPU\'s, but I noticed that both threads were running on the same CPU. I manually set one thread\'s affinity for the unused CPU and now am getting full utilization, but I am wondering why both models would end up on the same CPU. Is Windows fully responsible for CPU affinity or can BOINC assign affinities to maximize utlization?

I recognize that my memory may be a limitation for this particular project, but the change in CPU affinity had no affect on memory consumption. My Dell laptop\'s second memory slot died on me and this is why I\'m short on RAM.

BOINC: v5.10.45
OS: Windows Vista Business (non-SP1)
CPU: Dual 1.6GHz Intel T2060
RAM: 1Gb

BOINC does not manipulate processor affinity - though someone has compiled a version of the BOINC Manager that does just that. Whether it\'s up-to-date I don\'t know (i.e. 5.10.45).

Normally, the active processes will use both processors if both processors are enabled in the BIOS. Note, however, that the CPDN application has two processes per model (and sometimes a third, intermittent, one). If you use processor affinity to control a slab model - as you have done - then you should set both processes for each model to the same affinity. This is because the process that does the work terminates at the end of a phase and a new one is started: if the control process has the same affinity then the worker process for the new phase will carry on using the same processor as for the previous phase. If you start and stop BOINC then setting affinities - particularly in Vista - is a pain, and shoudn\'t be necessary.

I don\'t know why your two models were trying to run on the same processor and leaving the other idle. I apply affinities to most of my multi-core PCs and have never seen that behaviour.

Iain, could it have something to do with having only one Gig of RAM? That\'s barely enough to run Vista, let alone applications on Vista. Running CPDN, especially two copies, might pound the page/swap files heavily.

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"We have met the enemy and he is us." -- Pogo
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... that would certainly explain why I haven\'t seen it! All my 32-bit Vista PCs have maximum RAM. However, I can\'t see what advantage the operating system thinks it\'s getting by avoiding one processor when short of RAM. And slabs aren\'t that demanding.

... that would certainly explain why I haven\'t seen it! All my 32-bit Vista PCs have maximum RAM. However, I can\'t see what advantage the operating system thinks it\'s getting by avoiding one processor when short of RAM. And slabs aren\'t that demanding.

Agreed. My system, though RAM challenged, does a gine job of splitting all other tasks among the dual cores. This issue with BOINC was the only time I\'ve ever noticed this behavior, but it hasn\'t happened since. After setting the affinity for one thread to the other core, BOINC has restarted numerous times and Vista has properly put each thread on its own core just as I\'d expect. Perhaps this was just a fluke. When in doubt, I blame Windows. This approach has proved accurate since I was first disappointed by Windows3.1, so I\'m sticking with it ;).

I don\'t get a lot of swapping, either, so even with 1Gb of memory, I\'m not as bad off as I fully expected when the other slot failed. I tend to run above 1Gb of total commit, but much of this is due to inactive tasks that can be paged without consequence until I use them. I never run Aero (expensive eye candy) and am very strict about even which background tasks and optional services I run, so 1Gb is only frustrating when I start doing video editing ;). Yea, really. Dell isn\'t jumping at the opportunity to swap out my laptop motherboard or send me a new one, but I certainly need another 1Gb just to lower the frustrating factor.

Thanks for the great responses. Be well.