virtio — archive

[PATCH v6 0/5] packed ring layout spec

From: Michael S. Tsirkin <[email protected]>
To: [email protected]
Date: Wed, 10 Jan 2018 15:37:00 -0000

On Wed, Jan 10, 2018 at 03:15:38PM +0100, Cornelia Huck wrote: > On Wed, 10 Jan 2018 11:47:58 +0200 > "Michael S. Tsirkin" <[email protected]> wrote: > > > Performance analysis of this is in my kvm forum 2016 presentation. The > > idea is to have a r/w descriptor in a ring structure, replacing the used > > and available ring, index and descriptor buffer. > > Do we have a place to store pointers to such information? > > > > > This is also easier for devices to implement than the 1.0 layout. > > Several more enhancements will be necessary to actually make this > > efficient for devices to use. > > > > Signed-off-by: Michael S. Tsirkin <[email protected]> > > --- > > content.tex | 36 ++- > > packed-ring.tex | 668 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 701 insertions(+), 3 deletions(-) > > create mode 100644 packed-ring.tex > > > > diff --git a/content.tex b/content.tex > > index 3b4579e..3059bd3 100644 > > --- a/content.tex > > +++ b/content.tex > > (...) > > > @@ -5199,10 +5215,19 @@ Currently these device-independent feature bits defined: > > \begin{description} > > \item[VIRTIO_F_RING_INDIRECT_DESC (28)] Negotiating this feature indicates > > that the driver can use descriptors with the VIRTQ_DESC_F_INDIRECT > > - flag set, as described in \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors}. > > + flag set, as described in \ref{sec:Basic Facilities of a Virtio > > +Device / Virtqueues / The Virtqueue Descriptor Table / Indirect > > +Descriptors}~\nameref{sec:Basic Facilities of a Virtio Device / > > +Virtqueues / The Virtqueue Descriptor Table / Indirect > > +Descriptors} and > > + \ref{sec:Packed Virtqueues / Indirect Flag: Scatter-Gather Support} > > +\ref{sec:Packed Virtqueues / Driver and Device Event Suppression}. > > That one needs to go below (copy/paste error?). > > > > > \item[VIRTIO_F_RING_EVENT_IDX(29)] This feature enables the \field{used_event} > > - and the \field{avail_event} fields as described in \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression} and \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring}. > > + and the \field{avail_event} fields as described in > > +\ref{sec:Basic Facilities of a Virtio Device / Virtqueues / > > +Virtqueue Interrupt Suppression}, \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring} > > +and . > > Here's where the ref above needs to go. > > > > > \item[VIRTIO_F_VERSION_1(32)] This indicates compliance with this > > specification, giving a simple way to detect legacy devices or drivers. > > @@ -5212,6 +5237,9 @@ Currently these device-independent feature bits defined: > > addresses in memory. If this feature bit is set to 0, then the device emits > > physical addresses which are not translated further, even though an IOMMU > > may be present. > > + \item[VIRTIO_F_RING_PACKED(34)] This feature indicates > > + support for the packed virtqueue layout as described in > > +\ref{sec:Basic Facilities of a Virtio Device / Packed Virtqueues}. > > \end{description} > > I think the references should include a title as well (that makes the > resulting document easier to read). Want to add a macro including ref+nameref? We'd use it for all sec: references then. > > > > \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}