Lately, Seti@home has been sending my duallie 2 WUs at a time.......

How is this set up? Are the individual processors actually processing one WU each, or are both processors jointly working on both units.....

I admit that it sounds like a stupid question, but if each processor is running one WU each, I would like to know what kind of commands have been written to accomplish this.......

Digital Audio dual 533

Tiger 10.4.3

Thanks,

Kevin

Yes, if you have the preferences option set to use 2 CPUs on multiprocessor machines, BOINC will run 2 results at the same time, with each processor handling one result. The default is 2, because of the many dual-core AMD chips out there, plus the availability of HyperThreading (a "fake" two cores) on some Pentiums - and of course, the many dual-processor Macs now available.

As far as how it's done, it's very simple, given a decent OS - the OS will pick for any given thread the CPU that is "less busy" at that moment. By simply running two copies of the science application, BOINC lets the OS take it from there, and if nothing else is running, that means each BOINC result gets one CPU. There are discussions on adding "processor affinity" to BOINC, where BOINC would actually specify "run this app on this CPU", which would give a little bit better performance (as it is, if you, or the OS, run some other app that takes up one CPU, even for a moment, the two BOINC threads will share the other CPU for a while, each getting only 50%, and this switching between CPUs causes a few 'wasted' cycles) but the performance gain from doing this is probably not worth the investment in programming time.

If you look in the "Work" tab of BOINC Manager, you'll see two results with status "running". Likewise, I understand the latest version of Menubar puts up two icons with two progress bars. While HyperThreading only gives a 10-20% overall improvement, with a true Dual like yours, you'll be able to do twice the work - just exactly as if you had two computers. Also, you might want to look seriously at the Altivec-optimized SETI applications available from Team MacNN - they cut the time _per_ result in half on a G4... BOINC offers a lot of advantages to Mac folks!

Hi Bill !

Thanks for the clearly-stated reply !

Re: AltiVec-optimized Boinc

I found the link for it earlier this evening, and will probably try it on my cloned partition Sun., or Mon.

Thanks Again,

Kevin

Re: AltiVec-optimized Boinc

I found the link for it earlier this evening, and will probably try it on my cloned partition Sun., or Mon.

Please be careful on what you install - you do NOT want the "optimized BOINC client" at this time. You want the "Optimized SETI application" (currently alpha-5, I think). Once you have been _running_ that application for a few days, _if_ your "claimed credit" is way low, THEN you may want to look at an optimized BOINC core client...

Hi again Bill !

I mis-stated the optimized Boinc thing due to mentally not seperating Boinc and Seti, which I have to get used to now, especially the way it operates with Seti as the only client on it.......

The link I had found was for the optimized Seti.......

Thanks Again,

Kevin

EDIT: for any other G4/G5 users, this link takes you to the discussion of the optimized Seti, and links to the downloads...