Date: Sun, 14 Sep 2008 20:38:00 -0500 From: Stephen Montgomery-Smith <stephen@math.missouri.edu> To: freebsd-current@freebsd.org Subject: Improved multiprocessor usage on amd64 Message-ID: <48CDBC78.4010409@math.missouri.edu>
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I have a dual core amd64 on which I run a processor intensive numerical program. I had been frustrated because it seemed to run 3 or 4 times faster under Linux. But with a recent upgrade of FreeBSD-CURRENT, it now goes at about the same speed as Linux. The program takes about an hour. For the first minute, the program runs rather slowly, but then it is as if the operating system finds its way, and suddenly it speeds up. "top -H" suggests that for the first minute that one thread is going really slowly, and is perhaps being starved or something. My question is - why is this happening, and is this something I should expect? Are there certain switches or sysctls I can set to make it go fast from the get go? I should add that I am gratified that FreeBSD has caught up with Linux in this respect. I hope that I will see even more improvements. I will be happy to share the software I am running to help in this regard, but I don't yet have permission from my employer (University of Missouri) to give it an open source license, so I only feel comfortable giving it to people on a case by case basis. Thanks, Stephen
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