Re: [9fans] Plan9 - the next 20 years

[erik quanstrom <quanstro@quanstro.net>]

> i was trying to point out that if you try to
> ignore the issue by removing flush from the
> protocol, you'll get a system that doesn't work so smoothly.

your failure cases seem to rely on poorly chosen tags.
i wasn't suggesting that flush be eliminated.  i was
thinking of ways of keeping flush self-contained.

if the tag space were enlarged so that we could require
that tags never be reused, flushes that do not flush anything
could be remembered.  the problem with this is it could
require a large memory of unprocessed flushes.  there
are lots of potential solutions to that problem.
one could allow the server to stall if too many martian
flushes were hanging about and allow clients to declare
they will reuse part of the tag space and asserting that
nothing within reused portion is outstanding.  you could
then keep the current definition of tag, though 16 bits
seems a bit small to me.

- erik