Re: vn(4) performance on 4.11 versus md(4) on 5.4

scuba_at_centroin.com.br
Date: 06/10/05

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    Date: Fri, 10 Jun 2005 12:09:10 -0300 (EST)
To: Glenn Dawson <glenn@antimatter.net>

    Hi Glenn,

            Have already fixed that problem?
            Your tests were on the same hardware?
            I´ve tested two of my boxes one with, FBSD 4.9 and another with
    the latest cvs 5.4.
            They´re not the same hardware but the performance with md drive
    was MUCH faster with 5.4.

            TEsted with 'dd':
            4.9:
    dd if=/dev/zero of=TESTE count=1000 bs=64k
    1000+0 records in
    1000+0 records out
    65536000 bytes transferred in 1.005721 secs (65163195 bytes/sec)

            5.4:
    dd if=/dev/zero of=TESTE count=1000 bs=64k
    1000+0 records in
    1000+0 records out
    65536000 bytes transferred in 0.241217 secs (271688824 bytes/sec)

    - Marcelo Souza

    On Sat, 4 Jun 2005, Glenn Dawson wrote:

    |
    |
    |
    |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.
    |If I should post this to another list please let me know. (I started here
    |in order to avoid cross posting.
    |
    |-Glenn
    |
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    |

    - Marcelo

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