From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 12/22] virtio_pci: allow duplicate capabilities. Date: Thu, 21 Mar 2013 19:13:19 +0200 Message-ID: <20130321171319.GD2994@redhat.com> References: <20130321151937.GB1454@redhat.com> <514B26BC.6010700@zytor.com> <20130321155810.GA1925@redhat.com> <514B2FA0.9000204@zytor.com> <20130321161143.GC1925@redhat.com> <514B3213.8070002@zytor.com> <20130321162636.GF1925@redhat.com> <514B3606.2090503@zytor.com> <20130321170706.GB2994@redhat.com> <514B3EAE.8000707@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <514B3EAE.8000707@zytor.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "H. Peter Anvin" Cc: virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Thu, Mar 21, 2013 at 10:09:02AM -0700, H. Peter Anvin wrote: > On 03/21/2013 10:07 AM, Michael S. Tsirkin wrote: > > > > I just think it does not apply to BIOS so much. A bigger issue for BIOS > > virtio performance is that it normally does not implement batching at > > all, to keep it simple and reduce memory usage it uses a small number > > (often 1) of outstanding buffers per queue. > > > > You asked for examples, so I gave one. There is no doubt that BIOS can > make use of this if available. > > What you describe above is of course a typical problem with BIOS. > > -hpa Right, thanks. Also thanks for the spec quote, I really think we should add the config cycle access as a guaranteed feature. It's easy and I expect all BIOS drivers to use it. -- MST