Re: [PATCHv3 1/2] virtio: support layout with avail ring before idx

2010-06-04 Thread Rusty Russell
On Fri, 4 Jun 2010 09:12:05 pm Michael S. Tsirkin wrote: > On Fri, Jun 04, 2010 at 08:46:49PM +0930, Rusty Russell wrote: > > I'm uncomfortable with moving a field. > > > > We haven't done that before and I wonder what will break with old code. > > With e.g. my patch, We only do this conditionall

Re: [PATCHv3 1/2] virtio: support layout with avail ring before idx

2010-06-04 Thread Michael S. Tsirkin
On Fri, Jun 04, 2010 at 08:46:49PM +0930, Rusty Russell wrote: > On Fri, 4 Jun 2010 08:05:43 pm Michael S. Tsirkin wrote: > > On Fri, Jun 04, 2010 at 12:04:57PM +0930, Rusty Russell wrote: > > > On Wed, 2 Jun 2010 12:17:12 am Michael S. Tsirkin wrote: > > > > This adds an (unused) option to put ava

Re: [PATCHv3 1/2] virtio: support layout with avail ring before idx

2010-06-04 Thread Rusty Russell
On Fri, 4 Jun 2010 08:05:43 pm Michael S. Tsirkin wrote: > On Fri, Jun 04, 2010 at 12:04:57PM +0930, Rusty Russell wrote: > > On Wed, 2 Jun 2010 12:17:12 am Michael S. Tsirkin wrote: > > > This adds an (unused) option to put available ring before control (avail > > > index, flags), and adds padding

Re: [PATCHv3 1/2] virtio: support layout with avail ring before idx

2010-06-04 Thread Michael S. Tsirkin
On Fri, Jun 04, 2010 at 12:04:57PM +0930, Rusty Russell wrote: > On Wed, 2 Jun 2010 12:17:12 am Michael S. Tsirkin wrote: > > This adds an (unused) option to put available ring before control (avail > > index, flags), and adds padding between index and flags. This avoids > > cache line sharing betw