Re: [NFS] [CFT] Improved RPC congestion handling for 2.4.0 (and 2.2.18)

["H . J . Lu" <hjl@valinux.com>]

On Mon, Jan 22, 2001 at 03:36:38PM -0800, H . J . Lu wrote:
> On Tue, Jan 23, 2001 at 12:00:29AM +0100, Trond Myklebust wrote:
> > >>>>> " " == H J Lu <hjl@valinux.com> writes:
> > 
> >      > I got a report which indicates it may not be a good idea,
> >      > especially for UDP. Suppose you have a lousy LAN or NFS UDP
> >      > server for whatever reason, some NFS/UDP packets may get lost
> >      > very easily while a ping request may get through. In that case,
> >      > the rpc ping may slow down the NFS client over UDP
> >      > significantly.
> > 
> > Hi HJ,
> > 
> > Could you clarify this? Don't forget that we only send the ping after
> > a major timeout (usually after 3 or more resends).
> > 
> > IOW: If the ping gets through, then it'll have cost us 1 RPC request,
> > which is hardly a major contribution when talking about timescales of
> > the order of 5 seconds which is what that major timeout will have cost
> > (Don't forget that RPC timeout values increase geometrically).
> > 
> 
> Michael Kriss <kriss@fnal.gov> is having this problem. I think this
> problem may be very specific to his network setup. I couldn't duplicate
> his problem. My guess is for his case, every ping sent is a loss of
> a potential working retry packet. He is using Solaris NFS sever with
> Linux client. I had an impression that packets from Solaris NFS server
> was dropped quite often. I don't know what happened.
> 

I believe it is a false alarm. It turned out that the interface was not
in the full duplex mode. After turning on autonego on switch,
everything seems fine now. Sorry for that.

-- 
H.J. Lu (hjl@valinux.com)
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