cvs commit: src/sys/dev/fxp if_fxp.c

[Brooks Davis]

On Mon, Jan 31, 2005 at 10:38:49PM +0000, Robert Watson wrote:
> 
> On Mon, 31 Jan 2005, John Baldwin wrote:
> 
> > On Saturday 29 January 2005 06:13 pm, Robert Watson wrote:
> > > rwatson     2005-01-29 23:13:20 UTC
> > >
> > >   FreeBSD src repository
> > >
> > >   Modified files:
> > >     sys/dev/fxp          if_fxp.c
> > >   Log:
> > >   Disable ethernet flow control in if_fxp by default, in order to prevent
> > >   unexpected surprises when a system panics or is left in the debugger.
> > 
> > Is this the bit that would cause the interface to start spewing pause
> > packets onto the network after a panic resulting in the whole network
> > being useless until the box is powered off? 
> 
> Yup, that's the one.  It's a feature :-).

It's worth noting that flowcontrol is of severely limited use in many
cases.  First, it doesn't differentiate between packets you want and
packets you don't.  Second, current switches don't generate it so if
several hosts are beating up on one (as happens if you have a clusters
file system), the switch won't tell them to back off and you start
losing packets in the switch.  TCP seriously sucks when you lose packets
in the LAN. :)

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.
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