Date: Sun, 05 Jun 2005 14:24:19 -0700 From: Glenn Dawson <glenn@antimatter.net> To: freebsd-hackers@freebsd.org Subject: vn(4) performance on 4.11 versus md(4) on 5.4 Message-ID: <6.1.0.6.2.20050605142135.040c89a0@cobalt.antimatter.net>
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(I sent this to freebsd-performance yesterday, but that list seems kind of dead, so I'm trying this one. If there's a better place for me to send this, let me know.) I have a number of systems running 4.11 that have file backed virtual disks, each of which contains a jail. I need to start using 5.4 for new servers. The catch is, file backed virtual disks using md(4) seem to be much slower than similar virtual disks on 4.11 using vn(4). vn(4) on 4.11 is about 2.24 times faster than the equivalent setup using md(4) on 5.4. I've posted the results of some tests that I ran at http://www.antimatter.net/md-versus-vn.txt Is this decrease in performance known? Is there something I can do in order to come close to the performance that 4.11 has? I've tried changing some of the parameters of the filesystem on the virtual disk, but the performance didn't change. I can supply more info than what the link above has, if needed. -Glenn
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