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To: piet@bluelane.com
Cc: "David S. Miller" <davem@davemloft.net>, torvalds@osdl.org,
       diegocg@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: Linux 2.6.17-rc2
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From: Andi Kleen <ak@suse.de>
Date: 21 Apr 2006 04:05:50 +0200
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Piet Delaney <piet@bluelane.com> writes:
> 
> FreeBSD folks developed a ZERO_COPY_SOCKET facility that uses COW; 
> code looked great.

Linux had patches many years ago (in 2.3.x), but it was never merged
because it is inherently unscalable on MP. Classical BSD sockets really 
don't work well for zero copy - you need a new interface (like POSIX aio) 
that allows the kernel/user to tell each other when use of data is
finished and buffers can be reused.

-Andi