[9fans] About 9P ... - Plan9

This is a discussion on [9fans] About 9P ... - Plan9 ; > Even with a local root, importing stuff over (say) wifi can be painful. perhaps there's something about your setup that's different than mine. even mounting root over a wireless connection is not a problem. my desktop machine is connected ...

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  1. Re: [9fans] 9P optimization

    > Even with a local root, importing stuff over (say) wifi can be painful.

    perhaps there's something about your setup that's different than
    mine. even mounting root over a wireless connection is not a problem.
    my desktop machine is connected a shared (with a dozen other computers)
    wireless bridge. the ping time of 3-4ms is not noticable unless one starts
    compiling the kernel locally. but cpu solves that problem quite nicely.

    datakit terminals had similar latency and worse bandwidth.

    at home, i have a 40ms ping time (surely your wireless connection is
    faster) to work servers. i sometimes notice just a slight delay saving
    files over an encrypted, imported connection. but since i compile over
    a cpu session, it's just not an issue.

    - erik

  2. Re: [9fans] 9P optimization

    On 6/24/07, Lyndon Nerenberg wrote:

    > 9P wouldn't need any mods -- this would work easily as a filter pushed on
    > the 9fs connection. But it would need a callback facility to notify the
    > server side of the cache filter that the file had changed.


    callback? Couldn't you just post a read on a file in the server and
    have a thread hang on that?

    ron

  3. Re: [9fans] 9P optimization

    There is some literature on the topic, e.g., AFS callbacks
    (later called "leases" in the NFS world) and Coda's variable-
    granularity callbacks... the problems aren't exactly the same,
    but it seems like there might well be an opportunity to learn
    from existing experience.

    This describes experience gained from a system with actual
    users (i.e., isn't just a simulation study):

    Exploiting Weak Connectivity for Mobile File Access
    http://www.cs.cmu.edu/~coda/docdir/s15.pdf

    Dave Eckhardt

  4. Re: [9fans] 9P optimization

    > perhaps there's something about your setup that's different than
    > mine.


    There is. When I tried it it was over a 11 Mb/s wireless link with much
    worse latency than you have. (We were seeing 200+ms RTTs to anywhere that
    mattered, with 15-20% packet loss.)

    --lyndon

    I love to sing, and I love to drink scotch. Most people would rather
    hear me drink scotch.
    -- George Burns

  5. Re: [9fans] 9P optimization

    > callback? Couldn't you just post a read on a file in the server and
    > have a thread hang on that?


    I was thinking more along the lines of a notify server where you would
    register pathnames of interest and post a read on a file that would
    receive the event notifications.

    --lyndon

    Never hit a man with glasses. Hit him with a baseball bat.

  6. Re: [9fans] 9P optimization

    that's pretty massive packet loss. tcp is likely to suffer mightily.

    i used dialup until last year. the rtt time to the gatway was 150ms and
    the provider was proud enough of their network to push the default mtu
    to 1500 bytes. i never measured any packet loss.

    perhaps you would have better luck with dialup?

    - erik

    On Mon Jun 25 13:48:55 EDT 2007, lyndon@orthanc.ca wrote:
    > There is. When I tried it it was over a 11 Mb/s wireless link with much
    > worse latency than you have. (We were seeing 200+ms RTTs to anywhere that
    > mattered, with 15-20% packet loss.)
    >
    > --lyndon


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