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From: rob pike rob@plan9.bell-labs.com
Subject: [9fans] Re: 9p question
Date: Thu,  9 Mar 2000 08:50:41 -0500	[thread overview]
Message-ID: <20000309135041.ADwV8IAtLjSXb6Qu9x7y2ueJ3JP7oknRKwV4P2vSIcQ@z> (raw)

> The real reason for the "lengthy" conversation is the Tclone/Twalk
> part.  That is part of the price that is paid to remove the '/' as a
> directory separator

No. The real reason is that after each walk the client must check whether
the point-so-far is in the mount table.  That's why it's done a path
element at a time, and why it's so slow.  Other designs have been
proposed that would allow a walk message to contain multiple
elements (requiring the server to parse and understand '/'), but
it's such a pain to change the protocol.

Seeking on a directory is forbidden because it's hard enough to
implement reading a union directory without seek. The internal
structure that must be maintained in the kernel was deemed too
hard to maintain other than by sequential access, so we made
seeking on a directory illegal.  It didn't seem worth the implementation
overhad.  I still feel that way.

>There are a lot of strange things like:
>     delim $$ define lbr ' roman "{" ' define rbr ' roman "}" '
>or
>     $CH sub c$
>which should be "CH <sub>c</sub>",  I guess.

Would you have noticed this if it didn't contain your name?

-rob





             reply	other threads:[~2000-03-09 13:50 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-03-09 13:50 rob [this message]
  -- strict thread matches above, loose matches on Subject: below --
2000-03-16 14:05 presotto
2000-03-14 14:51 forsyth
2000-03-13 12:01 Roman
2000-03-13  9:28 Douglas
2000-03-11 15:00 rob
2000-03-11  9:53 Vladimir
2000-03-10 11:02 forsyth
2000-03-10  9:23 Roman
2000-03-10  9:23 David
2000-03-09 19:04 forsyth
2000-03-09 18:10 Roman
2000-03-09 18:05 Roman
2000-03-09 15:33 presotto
2000-03-09 14:44 Roman
2000-03-09 14:21 Roman
2000-03-09 13:18 presotto
2000-03-09 10:50 forsyth
2000-03-09 10:39 forsyth
2000-03-09 10:02 Douglas
2000-03-09  9:26 Roman
2000-03-07  9:32 David
2000-02-28 18:07 rob

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