linux-kernel - Re: [RFC] [TCP 1/3] tcp: Add MSG_NEW_PACKET flag to indicate preferable packet boundaries

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Date:	Mon, 02 Jul 2012 13:00:56 +0200
From:	Andreas Gruenbacher <agruen@...bit.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [RFC] [TCP 1/3] tcp: Add MSG_NEW_PACKET flag to indicate
 preferable packet boundaries

On Fri, 2012-06-29 at 19:15 +0200, Eric Dumazet wrote:
> On Fri, 2012-06-29 at 17:38 +0200, Andreas Gruenbacher wrote:
> 
> > The primary use case is fast Gigabit (10 or more) Ethernet connections
> > with jumbo frames and switches that support them.  There, frames will go
> > through unchanged and you can zero-copy receive all the time.
> > 
> > Not sure how well the approach scales to other kinds of connections; it
> > may work often enough to be worth it.  When things get distorted between
> > the sender and the receiver and tcp_recvbio() fails, the data can still
> > be copied out of the socket as before.
> 
> If you have a packet loss, receiver can and will coalesce frames.

That's alright as long as we'll get "back to normal" eventually; the
only effect will be that we'll copy data out of the socket receive
buffers for a while.  There will be extremely little packet loss on the
kinds of networks that we want to use this on.

Thanks,
Andreas

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