On Fri, Feb 10, 2023 at 11:22:14AM +0200, Alvaro Karsz wrote:
> Thanks Heng.
>
> > Currently, the coalescing profile is directly applied to all queues.
> > This patch supports setting or getting the parameters for a specified queue,
> > and a typical application of this function is NetDIM.
> >
> > When the traffic between queues is unbalanced, for example, one queue
> > is busy and another queue is idle, then it will be very useful to
> > control coalescing parameters at the queue granularity.
> >
> > Signed-off-by: Heng Qi <[email protected]>
> > Reviewed-by: Xuan Zhuo <[email protected]>
> > ---
> > v1->v2:
> > 1. Rename VIRTIO_NET_F_PERQUEUE_NOTF_COAL to VIRTIO_NET_F_VQ_NOTF_COAL.
> > @Michael S. Tsirkin
> > 2. Use the \field{vqn} instead of the qid. @Michael S. Tsirkin
> > 3. Unify tx and rx control structres into one structure
> > virtio_net_ctrl_coal_vq. @Michael S. Tsirkin
> > 4. Add a new control command VIRTIO_NET_CTRL_NOTF_COAL_VQ. @Michael S.
> > Tsirkin, @Parav Pandit, @Alvaro Karsz
> > 5. The special value 0xFFF is removed because VIRTIO_NET_CTRL_NOTF_COAL
> > can be used. @Alvaro Karsz
> > 6. Clarify some special scenarios. @Michael S. Tsirkin, @Parav Pandit,
> > @Alvaro Karsz
> >
> > content.tex | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 68 insertions(+), 1 deletion(-)
> >
> > diff --git a/content.tex b/content.tex
> > index e863709..2c497e1 100644
> > --- a/content.tex
> > +++ b/content.tex
> > @@ -3084,6 +3084,9 @@ \subsection{Feature bits}\label{sec:Device Types /
> > Network Device / Feature bits
> > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
> > channel.
> >
> > +\item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports the virtqueue
> > + notifications coalescing.
> > +
> > \item[VIRTIO_NET_F_NOTF_COAL(53)] Device supports notifications coalescing.
> >
> > \item[VIRTIO_NET_F_GUEST_USO4 (54)] Driver can receive USOv4 packets.
> > @@ -3140,6 +3143,7 @@ \subsubsection{Feature bit
> > requirements}\label{sec:Device Types / Network Device
> > \item[VIRTIO_NET_F_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ.
> > \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or
> > VIRTIO_NET_F_HOST_TSO6.
> > \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ.
> > +\item[VIRTIO_NET_F_VQ_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ and
> > VIRTIO_NET_F_NOTF_COAL.
> > \end{description}
> >
>
> Do we need VIRTIO_NET_F_CTRL_VQ in this case?
> VIRTIO_NET_F_VQ_NOTF_COAL requires VIRTIO_NET_F_NOTF_COAL, which
> requires VIRTIO_NET_F_CTRL_VQ, so it's implied.
>
> We have a similar example with VIRTIO_NET_F_HOST_ECN, which requires
> VIRTIO_NET_F_HOST_TSO4 or VIRTIO_NET_F_HOST_TSO6.
> VIRTIO_NET_F_CSUM is not mentioned here, although required.
>
> So, should we remove VIRTIO_NET_F_CTRL_VQ here, or fix VIRTIO_NET_F_HOST_ECN?
Ah good point.
But I think VIRTIO_NET_F_VQ_NOTF_COAL should not depend on
VIRTIO_NET_F_NOTF_COAL.
This way devices can drop the all-rx/all-tx commands if they want to.
> > \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types /
> > Network Device / Feature bits / Legacy Interface: Feature bits}
> > @@ -4520,6 +4524,49 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> > \item VIRTIO_NET_CTRL_NOTF_COAL_RX_SET: set the \field{rx_usecs} and
> > \field{rx_max_packets} parameters.
> > \end{enumerate}
> >
> > +If additionally VIRTIO_NET_F_VQ_NOTF_COAL is negotiated, the driver can
> > send
> > +control commands to set or get the coalescing parameters of a specified
> > +virtqueue (excluding the control virtqueue).
> > +
> > +\begin{lstlisting}
> > +struct virtio_net_ctrl_coal_vq {
> > + le32 max_packets;
> > + le32 usecs;
> > + le16 vqn;
> > +};
> > +
> > +#define VIRTIO_NET_CTRL_NOTF_COAL_VQ 7
> > + #define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET 0
> > + #define VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET 1
> > +\end{lstlisting}
> > +
>
> We already have a notifications coalescing class, why not group all
> coalescing commands under a single class?
Agree here.
>
> > +Virtqueue coalescing parameters:
> > +\begin{itemize}
> > +\item \field{max_packets}: The maximum number of packets sent/received by
> > the
> > + specified virtqueue before a TX/RX notification.
> > +\item \field{usecs}: The maximum number of TX/RX usecs that the specified
> > + virtqueue delays a TX/RX notification.
> > +\item \field{vqn}: The virtqueue number of the specified virtqueue.
> > +\end{itemize}
> > +
> > +The range of \filed{vqn} is between 0 and 0xFFFF inclusive, $ \lfloor vqn
> > / 2 \rfloor $
> > +is the index of the corresponding receiveq, and $\lfloor (vqn / 2) + 1
> > \rfloor $ is
> > +the corresponding tranmitq.
> > +
> > +The VIRTIO_NET_CTRL_NOTF_COAL_RX_SET command is the same as calling
> > VIRTIO_NET_CTRL_NOTF_COAL_VQ
> > +for virtqueues corresponding to all receiveqs.
> > +
> > +The VIRTIO_NET_CTRL_NOTF_COAL_TX_SET command is the same as calling
> > VIRTIO_NET_CTRL_NOTF_COAL_VQ
> > +for virtqueues corresponding to all transmitqs.
> > +
> > +Virtqueue coalescing will be disabled if all parameters are set to 0.
> > +
> > +The class VIRTIO_NET_CTRL_NOTF_COAL_VQ has 2 commands:
> > +\begin{enumerate}
> > +\item VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET: set the \field{max_packets},
> > \field{usecs} and \filed{vqn} parameters.
> > +\item VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET: get the \field{max_packets},
> > \field{usecs} and \field{vqn} parameters.
> > +\end{enumerate}
> > +
> > \subparagraph{RX Notifications}\label{sec:Device Types / Network Device /
> > Device Operation / Control Virtqueue / Notifications Coalescing / RX
> > Notifications}
> >
> > If, for example:
> > @@ -4535,6 +4582,15 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> > \item If the notifications are not suppressed by the driver, the device
> > will send an used buffer notification, otherwise, the device will not send
> > an used buffer notification as long as the notifications are suppressed.
> > \end{itemize}
> >
> > +If, example of setting coalescing parameters for a receive virtqueue:
> > +\begin{itemize}
> > +\item \field{max_packets} = 15.
> > +\item \field{usecs} = 10.
> > +\item \field{vqn} = 0;
> > +\end{itemize}
> > +
> > +The device will only operate on recieveq1 as
> > VIRTIO_NET_CTRL_NOTF_COAL_RX_SET.
> > +
> > \subparagraph{TX Notifications}\label{sec:Device Types / Network Device /
> > Device Operation / Control Virtqueue / Notifications Coalescing / TX
> > Notifications}
> >
> > If, for example:
> > @@ -4550,13 +4606,24 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> > \item If the notifications are not suppressed by the driver, the device
> > will send an used buffer notification, otherwise, the device will not send
> > an used buffer notification as long as the notifications are suppressed.
> > \end{itemize}
> >
> > +If, example of setting coalescing parameters for a transmit virtqueue:
> > +\begin{itemize}
> > +\item \field{max_packets} = 15.
> > +\item \field{usecs} = 10.
> > +\item \field{vqn} = 1;
> > +\end{itemize}
> > +
> > +The device will only operate on transmitq1 as
> > VIRTIO_NET_CTRL_NOTF_COAL_TX_SET.
> > +
> > \drivernormative{\subparagraph}{Notifications Coalescing}{Device Types /
> > Network Device / Device Operation / Control Virtqueue / Notifications
> > Coalescing}
> >
> > If the VIRTIO_NET_F_NOTF_COAL feature has not been negotiated, the driver
> > MUST NOT issue VIRTIO_NET_CTRL_NOTF_COAL commands.
> > +If the VIRTIO_NET_F_VQ_NOTF_COAL feature has not been negotiated, the
> > driver MUST NOT issue VIRTIO_NET_CTRL_NOFT_COAL_VQ commands.
> >
> > \devicenormative{\subparagraph}{Notifications Coalescing}{Device Types /
> > Network Device / Device Operation / Control Virtqueue / Notifications
> > Coalescing}
> >
> > -A device SHOULD respond to the VIRTIO_NET_CTRL_NOTF_COAL commands with
> > VIRTIO_NET_ERR if it was not able to change the parameters.
> > +A device SHOULD respond to the VIRTIO_NET_CTRL_NOTF_COAL commands with
> > VIRTIO_NET_ERR if it was not able to change the parameters or
> > +was not able to find a virtqueue using the \field{vqn}.
> >
> > A device SHOULD NOT send used buffer notifications to the driver, if the
> > notifications are suppressed as explained in \ref{sec:Basic Facilities of a
> > Virtio Device / Virtqueues / Used Buffer Notification Suppression}, even if
> > the coalescing counters expired.
> >
> > --
> > 2.19.1.6.gb485710b
> >
> >
> > This publicly archived list offers a means to provide input to the
> > OASIS Virtual I/O Device (VIRTIO) TC.
> >
> > In order to verify user consent to the Feedback License terms and
> > to minimize spam in the list archive, subscription is required
> > before posting.
> >
> > Subscribe: [email protected]
> > Unsubscribe: [email protected]
> > List help: [email protected]
> > List archive: https://lists.oasis-open.org/archives/virtio-comment/
> > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
> > List Guidelines:
> > https://www.oasis-open.org/policies-guidelines/mailing-lists
> > Committee: https://www.oasis-open.org/committees/virtio/
> > Join OASIS: https://www.oasis-open.org/join/
> >
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
