Re: [NFS] RE: [autofs] multiple servers per automount

From: Mike Waychison (Michael.Waychison_at_Sun.COM)
Date: 10/14/03

  • Next message: Tim Shepard: "[PATCH] fix numbering of lines in /proc/net/tcp (linux-2.6.0-test7)" 
    Date:	Tue, 14 Oct 2003 11:52:22 -0400
To: Ian Kent <raven@themaw.net>

    Ian Kent wrote:

    >On Tue, 14 Oct 2003, Joseph V Moss wrote:
    >
    >
    >
    >>The limit is 800 as others have stated. Although, it can be less than that
    >>if something else is already using up some of the reserved UDP ports.
    >>
    >>I wrote a patch long ago against a 2.2.x kernel to enable it to use
    >>multiple majors for NFS mounts (like the patches now common in several
    >>distros). I then ran into the 800 limit in the RPC layer. After changing
    >>the RPC layer to count up from 0, instead of down from 800, with no real
    >>upper limit, I was able to mount more than 2000 NFS filesystems simultaneously.
    >>I'm sure I could have done many thousand if I had had that many filesystems
    >>around to mount. Obviously, after 1024, it wasn't using reserved ports
    >>anymore, but it didn't seem to matter.
    >>
    >>Unfortunately, while the changes to NFS were easy to port to the 2.4 kernel,
    >>the RPC layer is different enough between 2.2 and 2.4 that it didn't work
    >>right off. Bumping it up to somewhere around 1024 should work, but using
    >>non-reserved ports didn't seem to work when I made a simple attempt.
    >>
    >>Of course, the real fix for the NFS layer is the expansion of the minor
    >>numbers that's already occurred in 2.6 and the RPC layer problems should
    >>be fixed by multiplexing multiple mounts on the same port.
    >>
    >>
    >>
    >>
    >
    >I don't see that expansion in 2.6 (test6). It looks to me like the
    >allocation is done in set_anon_super (in fs/super.c) and that looks like
    >it is restricted to 256. Please correct this for me. I can't see how there
    >is any change to the number of unnmaed devices.
    >
    >
    >

    Here is the quick fix for this in RH 2.1AS kernels:

    http://www.kernelnewbies.org/kernels/rh21as/SOURCES/linux-2.4.9-moreunnamed.patch

    It makes unnamed block devices use majors 12, 14, 38, 39, as well as 0.

    I don't know if anyone is working out a better scheme for
    get_unnamed_dev in 2.6 yet. It does need to be done though. A simple
    patch for 2.6 would maybe see the unnamed_dev_in_use bitmap grow to
    PAGE_SIZE, automatically allowing for 32768 unnamed devices.

    Mike Waychison

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  • Next message: Tim Shepard: "[PATCH] fix numbering of lines in /proc/net/tcp (linux-2.6.0-test7)"

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