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

2010-06-06 Thread Michael S. Tsirkin
On Sat, Jun 05, 2010 at 01:40:26PM +0930, Rusty Russell wrote: 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

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 between

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 between

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 available

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

2010-06-03 Thread Rusty Russell
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 between control and ring, and also makes it possible to extend avail control

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

2010-06-01 Thread Michael S. Tsirkin
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 between control and ring, and also makes it possible to extend avail control without incurring extra cache misses. Signed-off-by: