BOINC Q&A — 09/30/06

Can you explain more on Average CPU efficiency and Result Duration Correction Factor? There seems to be some confusion about this, and little definite knowledge. For instance, some say a lower RDCF is better, others say an RDCF closer to 1.0 is best. Which is the truth?

CPU efficiency is the difference between how much CPU time a process received relative to the amount of wall clock time that has passed. It is the answer to the question of “In the last ten minutes or so, how much CPU did BOINC based science applications receive?” The thing to remember here is that the OS is constantly doing things in the background and each of those things eats a little bit of the CPU.

Duration Correction Factor is a per project value that measures the difference between the the expected time to process a result based on the benchmark verses what it actually took. A score of 1.0 means that the benchmark and the application processing time are in sync. The lower the score the greater the variance between what the benchmarks predict verse what it actually took to complete the result.

BOINC tries very hard not to ask for more work than it can actually process in a given period of time, so it tries to keep track of the machine overhead by the CPU efficiency score and Duration Correction Factor. Another thing to keep in mind is that memory speed plays a big part in the Duration Correction Factor. When you see similar processing times for a result for a 3.0Ghz processor and a 2.0Ghz processor it normally means that the 3.0Ghz processor is running with memory that cannot keep up with the processor. Or that both processors are bottlenecked with the memory speed.

We haven’t come up with a good solution for measuring the memory bandwidth problem yet. However, we are working on it.

BOINC version release notes do not seam as complete as they were before or am I looking in the incorrect places?

You can checkout the latest and greatest changes to BOINC at this web address:
http://setiathome.berkeley.edu/cgi-bin/cvsweb.cgi/boinc/

The file you’ll want to look at is ‘checkin_notes’ which contains the latest changes made to the client and sever packages.

You can see the check-in history for a specific branch by changing the tag specified near the bottom of the web page. The 5.6 branch tag is ‘boinc_core_release_5_6’. If you want to see the changes for 5.4 you would use ‘boinc_core_release_5_4’ and on it goes.

Any plans on releasing the full minutes of what went on (when your back), I read up on the 1st one but was a bit disappointed with the info on show it only gave a brief overview of what went on.

You can find the workshop proceedings here:
http://boinc.berkeley.edu/ws_06.php

How was the vacation?

I had a blast. I met a bunch of great people. I’m looking forward to going again next year.

wxWidgets 2.7 has been released. Is this going to be used in 5.6 or is it too late?

Too late for this release.

I’ve seen and myself tried to compile 5.4.x using Microsoft’s free Visual Studio Express 2005 editions (with all the bits and bobs needed, wxWidgets, SDK that needed..) Errors show up and does not compile. Is this fixed in 5.6, given this would probably be the major environment used by people trying develop BOINC under windows (since it’s free).

The BOINC DLL relies upon the ATL libraries which are not included in the express editions of the MS Development tools. I’m not sure if this is going to change in the future or not. I suspect that if we can incorporate a torrent library that doesn’t use COM/DCOM on Windows then I’ll invest more time into removing the need for ATL/COM/DCOM so that the DLL can be built with VS Express.

On a side note, I do not believe the express editions of the Visual Studio toolset contain the optimizing compilers or linkers. You might have to upgrade for those, or use the GCC toolset’s.

Would it be possible for you (since afaik you compile the final Windows releases) to put up instruction on how you compile BOINC. This may help a lot of people who just wish to dabble.

I’ll see what I can do.

How is the progress on low-latency-computing? Which projects expressed their interest in this feature?

I believe this feature was put in for a hospital who wished to be able to process MRI images faster than their current method. I’m not sure this feature will be used by a public project in the near future.

To submit questions for next week just click on the comments link below and submit your question.

Thanks in advance.

—– Rom

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