Re: [9fans] Interested in improving networking in Plan 9

[erik quanstrom <quanstro@quanstro.net>]

> Try this - build the source to charon over a 200ms link over 9p. Then
> try again over sshfs.

why would you do this?  why not run the compile closer to
the source.  this is the power of plan 9.

> Also, look at a single terminal with a local fossil install. Trace the
> path of an 'ls /'. Count the number of copies and context switches.
>
> Having the fastest file server in the world means nothing for file
> system performance when your path to it is a maze of twisty passages,
> all alike.

again, this is not a typical install for a performance-sensitive
system.  and i don't know that anyone ever claimed fossil
to be a high-performance file system.  running a file system in user
space is a matter of convienence, not performance.

at coraid, we run a stand-alone ken's file server.  ken's file
server has no user space.  so while there are context switches,
those are really speedy.  they take maybe a few hundred cycles.
the real win is that no data is copied from/to user space and
there is one global page table that is never changed.  there are
no tlb flushes.  those can hurt.

before the switch to nupas, we averaged 200MB/s of fileserver traffic
during the day to >50 clients on a single, fairly pedestrian
xeon 5000 machine with 3.5gb of usable memory.

perhaps my standards are low and i'm out of touch, but i don't
think nfs could do that well with that little.

- erik