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From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Steve Dickson <SteveD@RedHat.com>
Cc: Brian Mancuso <bmancuso@akamai.com>, nfs@lists.sourceforge.net
Subject: Re: NFS/UDP slow read, lost fragments
Date: Tue, 14 Oct 2003 10:52:24 -0400	[thread overview]
Message-ID: <16268.3496.615917.119237@charged.uio.no> (raw)
In-Reply-To: <3F8B4F7B.4010907@RedHat.com>

>>>>> " " == Steve Dickson <SteveD@RedHat.com> writes:

     > As you can see the patches does help a little bit but but not
     > as much as I would expect.... Maybe it was the type of testes
     > ran or maybe I didn't run the tests long enough (each test ran
     > for about ~2mins) or maybe my expectations are too high... But
     > it just doesn't seem that these patches really help that much
     > in bringing down the retransmissions...

Thanks for putting numbers to this Steve!

Could you try using the slight variation in

 http://www.fys.uio.no/~trondmy/src/2.4.23-pre7/linux-2.4.23-03-fix_retrans.dif

As you can see, that has a slight change to rpc_set_timeo(): if it
sees that several retransmissions have occurred for a given request,
then it keeps the value of rtt->ntimeouts high for a couple of extra
iterations in order to allow the new value of the timeout to
converge.
The reason for doing this is that if the round trip time changes
suddenly, then it will takes ~ 8 measurements before you converge on
the new value (due to the weighting done in the algorithm).

Cheers,
  Trond


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  reply	other threads:[~2003-10-14 14:52 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-09-25 17:59 NFS/UDP slow read, lost fragments Robert L. Millner
2003-09-25 20:22 ` Brian Mancuso
2003-09-25 20:33 ` brianm
2003-09-25 21:44 ` Brian Mancuso
2003-09-25 23:31   ` Trond Myklebust
2003-09-26 21:07     ` Brian Mancuso
2003-09-27  5:02       ` Robert L. Millner
2003-10-14  1:20       ` Steve Dickson
2003-10-14 14:52         ` Trond Myklebust [this message]
2003-10-15  3:17           ` Steve Dickson
2003-10-15  3:27             ` Trond Myklebust
2003-09-25 20:11 Lever, Charles

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