linux-kernel - Re: [PATCHv2 RFC 0/4] virtio and vhost-net capacity handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 06 Jun 2011 13:09:35 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	"Michael S. Tsirkin" <mst@...hat.com>, linux-kernel@...r.kernel.org
Cc:	Carsten Otte <cotte@...ibm.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	linux390@...ibm.com, Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Shirley Ma <xma@...ibm.com>, lguest@...ts.ozlabs.org,
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
	linux-s390@...r.kernel.org, kvm@...r.kernel.org,
	Krishna Kumar <krkumar2@...ibm.com>,
	Tom Lendacky <tahm@...ux.vnet.ibm.com>, steved@...ibm.com,
	habanero@...ux.vnet.ibm.com
Subject: Re: [PATCHv2 RFC 0/4] virtio and vhost-net capacity handling

On Thu, 2 Jun 2011 20:17:21 +0300, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> On Thu, Jun 02, 2011 at 06:42:35PM +0300, Michael S. Tsirkin wrote:
> > OK, here's a new attempt to use the new capacity api.  I also added more
> > comments to clarify the logic.  Hope this is more readable.  Let me know
> > pls.
> > 
> > This is on top of the patches applied by Rusty.
> > 
> > Warning: untested. Posting now to give people chance to
> > comment on the API.
> > 
> > Changes from v1:
> > - fix comment in patch 2 to correct confusion noted by Rusty
> > - rewrite patch 3 along the lines suggested by Rusty
> >   note: it's not exactly the same but I hope it's close
> >   enough, the main difference is that mine does limited
> >   polling even in the unlikely xmit failure case.
> > - added a patch to not return capacity from add_buf
> >   it always looked like a weird hack
> > 
> > Michael S. Tsirkin (4):
> >   virtio_ring: add capacity check API
> >   virtio_net: fix tx capacity checks using new API
> >   virtio_net: limit xmit polling
> >   Revert "virtio: make add_buf return capacity remaining:
> > 
> >  drivers/net/virtio_net.c     |  111 ++++++++++++++++++++++++++----------------
> >  drivers/virtio/virtio_ring.c |   10 +++-
> >  include/linux/virtio.h       |    7 ++-
> >  3 files changed, 84 insertions(+), 44 deletions(-)
> > 
> > -- 
> > 1.7.5.53.gc233e
> 
> 
> And just FYI, here's a patch (on top) that I considered but
> decided against. This does a single get_buf before
> xmit. I thought it's not really needed as the capacity
> check in add_buf is relatively cheap, and we removed
> the kick in xmit_skb. But the point is that the loop
> will now be easy to move around if someone manages
> to show this benefits speed (which I doubt).

Agreed.  The other is clearer.

I like the approach these patches take.  Testing is required, but I
think the final result is a neater driver than the current one, as well
as having nicer latency.

Thanks,
Rusty.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/