Subject: Re: TSO and IPoIB performance degradation
From: Arjan van de Ven <arjan@infradead.org>
To: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: "Michael S. Tsirkin" <mst@mellanox.co.il>,
       "David S. Miller" <davem@davemloft.net>, rick.jones2@hp.com,
       netdev@vger.kernel.org, rdreier@cisco.com, linux-kernel@vger.kernel.org,
       openib-general@openib.org
In-Reply-To: <20060320114933.GA3058@xi.wantstofly.org>
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Date: Mon, 20 Mar 2006 12:53:35 +0100
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On Mon, 2006-03-20 at 12:49 +0100, Lennert Buytenhek wrote:
> On Mon, Mar 20, 2006 at 12:47:03PM +0100, Arjan van de Ven wrote:
> 
> > > > I disagree with Linux changing it's behavior.  It would be great to
> > > > turn off congestion control completely over local gigabit networks,
> > > > but that isn't determinable in any way, so we don't do that.
> > > 
> > > Interesting. Would it make sense to make it another tunable knob in
> > > /proc, sysfs or sysctl then?
> > 
> > that's not the right level; since that is per interface. And you only
> > know the actual interface waay too late (as per earlier posts).
> > Per socket.. maybe
> > But then again it's not impossible to have packets for one socket go out
> > to multiple interfaces
> > (think load balancing bonding over 2 interfaces, one IB another
> > ethernet)
> 
> I read it as if he was proposing to have a sysctl knob to turn off
> TCP congestion control completely (which has so many issues it's not
> even funny.)

owww that's so bad I didn't even consider that

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