Subject: Re: Packet mmap: TX RING and zero copy

From: Evgeniy Polyakov <[email-masked]>
Date: Tue, 2 Sep 2008 23:46:04 +0400

Hi Johann.

On Tue, Sep 02, 2008 at 08:27:36PM +0200, Johann Baudy ([email-masked]) wrote:
> I've made lot of tests, playing with jumbo frames, raw sockets, ...
> I've never exceeded ~25Mbytes/s. So I've decided to analyze deeply the
> packet socket transmission process.
> 
> The main blocking point was the memcpy_fromiovec() function that is
> located in the packet_sendmsg() of af_packet.c.

Can you saturate the link with usual tcp/udp socket?

> But, I would like to get as much criticism as possible in order to
> start a discussion with experts about a conceivable way to mix
> zero-copy, sk_buff management and packet socket.
> Which is perhaps impossible with current network kernel flow ...

Did you try vmsplice and splice?
It is the preferred way to do a zero-copy.

-- 
	Evgeniy Polyakov