Author: Robert Hyatt
Date: 13:39:49 02/18/03
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On February 18, 2003 at 16:08:49, Charles Worthington wrote: >Bob, the test results from the Intel site show a hyperthreading speed-up between >1.07 and 1.37 for various types of applications. I am no programmer but I am >speculating that since chess engines are designed specifically to run on >mulitiple threads and since they are known to monopolize 100% of cpu resources >that they will be rather high on this multiplier scale. What are your >observations with Crafty? Have you come up with a multiplier based on your own >observations? I haven't done any _exhaustive_ testing. I ran one test suite when I first got the machine and the raw NPS went up by 30%. I think Eugene also posted a similar number. I then ran a different test suite of 24 positions and the raw NPS was up by something just over 20%. Both of these were run prior to my fiddling with the spinlock code in crafty to add the pause ASM instruction, although I am not sure that made a very significant difference after using it a bit. I'll try to run the tests again, the only drawback is that it is necessary to re-boot the machine to turn it on/off, which means I have to be in my office to do the f2=setup stuff, which is not so convenient. I hate to shut down during the day, and although I can reboot from home, I can't change the BIOS settings from home... It does work, however. Eugene reported that running two copies of the tablebase compression/ decompression code at one time speeds up by a factor of 2x. (!!) which is _outstanding_. I have not tried to test _anything_ other than crafty. In linux, make -j would be a good test for seeing how multiple compiles speed up, etc...
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