From mboxrd@z Thu Jan  1 00:00:00 1970
From: Asias He <asias@redhat.com>
Subject: Re: [PATCH 4/6] virtio_ring: virtqueue_add_outbuf /
	virtqueue_add_inbuf.
Date: Thu, 7 Mar 2013 16:15:34 +0800
Message-ID: <20130307081534.GA19603@hj.localdomain>
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To: Rusty Russell <rusty@rustcorp.com.au>
Cc: mst@redhat.com, virtualization@lists.linux-foundation.org, sjur.brandeland@stericsson.com
List-Id: virtualization@lists.linuxfoundation.org

On Thu, Mar 07, 2013 at 11:33:19AM +1100, Rusty Russell wrote:
> Asias He <asias@redhat.com> writes:
> > On Wed, Mar 06, 2013 at 04:23:24PM +1100, Rusty Russell wrote:
> >> These are specialized versions of virtqueue_add_buf(), which cover
> >> over 80% of cases and are far clearer.
> >> 
> >> In particular, the scatterlists passed to these functions don't have
> >> to be clean (ie. we ignore end markers).
> >> 
> >> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> 
> >
> > So, what is the plan for the following ideas discussed in the other
> > thread?
> >
> >    '''
> >    > Looking at code, it seems that most users really have a single sg, in
> >    > low memory. So how about simply passing void * instead of sg? Whoever
> >    > has multiple sgs can use the rich interface.
> >    
> >    Good point, let's do that:
> >    1) Make virtqueue_add_outbuf()/inbuf() take a void * and len.
> >    2) Transfer users across to use that.
> >    3) Make everyone else use clean scatterlists with virtqueue_add_sgs[].
> >    4) Remove virtqueue_add_bufs().
> 
> Networking performance: there is still a performance penalty in using
> virtqueue_add_sgs(), and it can't use a simple void * and len.
> 
> So I changed my mind.  Again...

Ah, OK.

> Cheers,
> Rusty.

-- 
Asias