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[ale] networking backpressure

TCP. And yes, Windblows makes a totally shitty NFS product. It matches most
everything else they make (Excel is a noted exception).

On Wed, Apr 10, 2013 at 11:05 AM, Derek Atkins <warlord at mit.edu> wrote:

> Jim,
> Jim Kinney <jim.kinney at gmail.com> writes:
> > so what happens when a series of machines, each with 1G nic all try to
> read/
> > write to the same NFS mount filesystem, also on a single 1G nic, and
> this goes
> > on for hours at a time?
> >
> > Eventually, nic buffers fill and the OS is told to "hold that thought".
> But
> > for how long? Will the OS continue to try the write until it succeeds?
> Or will
> > the constant buffer overload just cause a nic to flush the buffer and
> hope for
> > better luck next send?
> Are you using UDP or TCP?
> If you're doing TCP then you just have to worry about buffer bloat.
> Beyond that, TCP will handle congestion control and should effectively
> rate-limit all clients.
> Using UDP, however, it's all a question of NFS's built-in congestion
> control.  This would depend on the version of the client and server.
> If your server is Windows, then I think you're probably screwed.  Their
> NFS server implementation has never been good.
> -derek
> --
>        Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
>        Member, MIT Student Information Processing Board  (SIPB)
>        URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
>        warlord at MIT.EDU                        PGP key available
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James P. Kinney III
*Every time you stop a school, you will have to build a jail. What you gain
at one end you lose at the other. It's like feeding a dog on his own tail.
It won't fatten the dog.
- Speech 11/23/1900 Mark Twain
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