Date: Thu, 9 Nov 1995 12:58:50 -0600 (CST) From: faulkner@mpd.tandem.com (Boyd Faulkner) To: bde@zeta.org.au (Bruce Evans) Cc: current@freebsd.org, faulkner@devnull Subject: Re: iozone and mount -o async Message-ID: <9511091858.AA27364@olympus> In-Reply-To: <199511090011.LAA16890@godzilla.zeta.org.au> from "Bruce Evans" at Nov 9, 95 11:11:21 am
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> > >Can you test the fs mounted async with iozone? I am getting a slowdown > >mounted async! > > This is normal. Mounting async disables the pessimization of doing > async (but ASAP) writes for full buffers. This pessimization is > actually an optimization for stupid benchmarks such as iozone. It > forces the physical i/o to be done ASAP instead of later when iozone > does an fsync(). Most applications don't do fsync()s so their i/o > gets done when the system thinks best. It might be useful to have > an fadvise() syscall (like madvise() but working :-). Applications > that do large sequential i/o's could use it to suggest write-through. > > Bruce > So how can I test my performance? iozone is no good. dd is no better. cp and cat file1 > file2 don't do as well either. It is because I am doing these things to a big file vs. a lot of smaller files? Thanks again, Boyd -- _______________________________________________________________________ Boyd Faulkner - faulkner@isd.tandem.com - http://cactus.org/~faulkner _______________________________________________________________________
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