Subject: Re: [PATCH 0/3] tun: fix aio

From: Rusty Russell <[email-masked]>
Date: Mon, 27 Apr 2009 10:48:37 +0930

On Mon, 20 Apr 2009 09:51:38 pm Michael S. Tsirkin wrote:
> On Mon, Apr 20, 2009 at 08:09:30PM +0800, Herbert Xu wrote:
> > Michael S. Tsirkin <[email-masked]> wrote:
> > >
> > > Note: I started out just allocating and copying the iovec rather than adding
> > > yet another skb-iterating routine, but this turned out to add small but
> > > measurable overhead on data path: tx time per packet jumped from 6500 to 6700 ns
> > > (let me know if you want to see that version of the patch).
> > 
> > Can you please post the copying version as well so we can compare?
> 
> Sure. Here it is: much smaller, but slightly slower.

Which could probably be fixed by using an on-stack version for a iovec
of less than a certain size...

Cheers,
Rusty.