On Mon, Oct 10, 2005 at 10:38:03AM -0400, Jeff Dike wrote: > On Mon, Oct 10, 2005 at 10:10:24AM +0100, Chris Lightfoot wrote: > > OK. The host is indeed using a 4K block filesystem; I > > couldn't find your O_DIRECT patch, but turning on O_DIRECT > > with fcntl just after opening the backing file gives these > > results: > > http://ex-parrot.com/~chris/tmp/20051010/host-vs-uml-io-results-3.png > > i.e., the AIO implementation is now slower than the stock > > implementation for writes of size up to about 8KB, but > > faster for larger writes; it's still quite a bit slower > > than the host. > > There aren't very good labels on that graph, but it looks consistent with my > experience, which is 25-30% faster kernel builds with AIO/O_DIRECT.
Not sure what additional labels you want, but here are the raw results (format as described previously): http://caesious.beasts.org/~chris/tmp/20051010/uml-2.6.12.5 http://caesious.beasts.org/~chris/tmp/20051010/uml-2.6.12.5-128M http://caesious.beasts.org/~chris/tmp/20051010/uml-2.6.12.5-newubd http://caesious.beasts.org/~chris/tmp/20051010/uml-2.6.13.3-aio http://caesious.beasts.org/~chris/tmp/20051010/uml-2.6.13.3-aio-direct http://caesious.beasts.org/~chris/tmp/20051010/host-2.6.13.3-skas3-v9-pre7-skas3-v7 http://caesious.beasts.org/~chris/tmp/20051010/host-cfq-2.6.13.3-skas3-v9-pre7-skas3-v7 -- names should be self-explanatory. > The next question is where the slowdown is happening. Well, it's got to be either O_DIRECT, aio, or breaking the requests up, I guess.... -- ``My years of hip-hop sessions came in handy as I could converse well with Fast Fingers. I knew the lingo and when to use it, and as far as he was concerned, I was one of the brothers. Strangely, neither of us was one of the brothers, but I figure that's just a technicality.'' (`MixerMan') ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
