Date: Fri, 07 Mar 2008 15:17:16 +0300 From: Dmitry Antipov <dmantipov@yandex.ru> To: freebsd-stable@freebsd.org Subject: [kern/sys_pipe.c] PIPE_NODIRECT and pipe throughput Message-ID: <47D1324C.80309@yandex.ru>
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Hello all, recently I've tried a few benchmarks around pipe throughput on Linux vs. FreeBSD. Everyone interesting can see my stuff at http://213.148.29.37/PipeBench, and initial post to Linux kernel developer mailing list at http://www.uwsg.iu.edu/hypermail/linux/kernel/0803.0/1837.html It was noticed (http://www.uwsg.iu.edu/hypermail/linux/kernel/0803.0/1842.html) that the page flipping may be a reason of FreeBSD advantage. I've looked at kern/sys_pipe.c and found that defining PIPE_NODIRECT should disable it. Is that correct ? Moreover, when I've tried to run the kernel (7.0-STABLE) with PIPE_NODIRECT defined, my benchmark didn't see 30% slowdown, as promised in kern/sys_pipe.c comments. So, what should be done with a pipe to see a difference between PIPE_NODIRECT enabled and disabled ? Dmitry
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