netdev - Re: [PATCH] LRO ack aggregation

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Date:	Tue, 20 Nov 2007 14:27:07 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	rick.jones2@...com
Cc:	gallatin@...i.com, netdev@...r.kernel.org, ossthema@...ibm.com
Subject: Re: [PATCH] LRO ack aggregation

From: Rick Jones <rick.jones2@...com>
Date: Tue, 20 Nov 2007 11:45:54 -0800

> Sounds like one might as well go ahead and implement HP-UX/Solaris-like 
> ACK sending avoidance at the receiver and not bother with LRO-ACK on the 
> sender.
> 
> In some experiements a while back I thought I saw that LRO on the 
> receiver was causing him to send fewer ACKs already?  IIRC that was with 
> a Myricom card, perhaps I was fooled by it's own ACK LRO it was doing.

Linux used to do aggressive ACK deferral, especially when the ucopy
code paths triggered.

I removed that code because I had several scenerios where it hurt more
than it helped performance, and the IETF has explicitly stated in
several documents the (proven) perils of such stretch ACKs.
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