On Tue, Feb 07, 2023 at 09:06:24AM -0500, Michael S. Tsirkin wrote:
> On Tue, Feb 07, 2023 at 07:16:34PM +0800, Heng Qi wrote:
> > Currently, the coalescing profile is directly applied to all queues.
> > This patch supports configuring the parameters for a specified queue.
> >
> > 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.
>
> ethtool does not support this though, does it? what's the plan?
>
> > Signed-off-by: Heng Qi <[email protected]>
> > Reviewed-by: Xuan Zhuo <[email protected]>
>
> What I dislike about this interface is that if
> VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, then
> in the common case of same parameters for all queues
> driver has to issue multiple commands.
> I can see either a special vq index (0xffff ?) or a special
> command used to set it for all queues.
Oh wait this is exactly what this patch did. Donnu why I missed this -
not enough coffee? Sorry pls ignore this part.
>
> > ---
> > content.tex | 49 ++++++++++++++++++++++++++++++++++++++++++-------
> > 1 file changed, 42 insertions(+), 7 deletions(-)
> >
> > diff --git a/content.tex b/content.tex
> > index e863709..049c0e4 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_PERQUEUE_NOTF_COAL(52)] Device supports per-queue
> > + 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_PERQUEUE_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ and
> > VIRTIO_NET_F_NOTF_COAL.
> > \end{description}
> >
> > \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types /
> > Network Device / Feature bits / Legacy Interface: Feature bits}
> > @@ -4488,16 +4492,21 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> >
> > If the VIRTIO_NET_F_NOTF_COAL feature is negotiated, the driver can
> > send control commands for dynamically changing the coalescing parameters.
> > +If additionally VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, the driver
> > +can send control commands to configure the coalescing parameters of a
> > +specified receiveq or transmitq.
> >
> > \begin{lstlisting}
> > struct virtio_net_ctrl_coal_rx {
> > le32 rx_max_packets;
> > le32 rx_usecs;
> > + le16 rx_qid; (Only if VIRTIO_NET_F_PERQUEUE_NOTF_COAL negotiated)
> > };
> >
> > struct virtio_net_ctrl_coal_tx {
> > le32 tx_max_packets;
> > le32 tx_usecs;
> > + le16 tx_qid; (Only if VIRTIO_NET_F_PERQUEUE_NOTF_COAL negotiated)
> > };
> >
> > #define VIRTIO_NET_CTRL_NOTF_COAL 6
>
> I think it's a good idea to do this on top of Alvaro's patch
> unifying these two structures.
>
> > @@ -4507,17 +4516,34 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> >
> > Coalescing parameters:
> > \begin{itemize}
> > -\item \field{rx_usecs}: Maximum number of usecs to delay a RX notification.
> > -\item \field{tx_usecs}: Maximum number of usecs to delay a TX notification.
> > +\item \field{rx_qid}: Index of which receiveq to change the coalescing
> > parameters.
> > + If the value is between 0 and 0x7FFF, it represents the index of the
> > specified
> > + receiveq. Otherwise, if the value is 0xFFFF, it indicates to change the
> > + coalescing parameters for all receiveqs.
>
> what if the index does not map to a receive queue?
>
> > +\item \field{tx_qid}: Index of which transmitq to change the coalescing
> > parameters.
> > + If the value is between 0 and 0x7FFF, it represents the index of the
> > specified
> > + transmitq. Otherwise, if the value is 0xFFFF, it indicates to change the
> > + coalescing parameters for all transmitqs.
> > +\item \field{rx_usecs}: Maximum number of usecs to delay a RX
> > notification. If additionally
> > + VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, it works for the
> > specified recieveq
> > + or all receieveqs.
> > +\item \field{tx_usecs}: Maximum number of usecs to delay a TX
> > notification. If additionally
> > + VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, it works for the
> > specified transmitq
> > + or all transmitqs.
> > \item \field{rx_max_packets}: Maximum number of packets to receive before
> > a RX notification.
> > + If additionally VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, it works
> > for the
> > + specified receiveq or all receiveqs.
> > \item \field{tx_max_packets}: Maximum number of packets to send before a
> > TX notification.
> > + If additionally VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated, it works
> > for the
> > + specified transmitq or all transmitqs.
> > \end{itemize}
> >
> > -
> > The class VIRTIO_NET_CTRL_NOTF_COAL has 2 commands:
> > \begin{enumerate}
> > -\item VIRTIO_NET_CTRL_NOTF_COAL_TX_SET: set the \field{tx_usecs} and
> > \field{tx_max_packets} parameters.
> > -\item VIRTIO_NET_CTRL_NOTF_COAL_RX_SET: set the \field{rx_usecs} and
> > \field{rx_max_packets} parameters.
> > +\item VIRTIO_NET_CTRL_NOTF_COAL_TX_SET: set the \field{tx_usecs} and
> > \field{tx_max_packets} parameters,
> > + and set the \field{tx_qid} if VIRTIO_NET_F_PERQUEUE_NOTF_COAL is
> > negotiated.
> > +\item VIRTIO_NET_CTRL_NOTF_COAL_RX_SET: set the \field{rx_usecs} and
> > \field{rx_max_packets} parameters,
> > + and set the \field{rx_qid} if VIRTIO_NET_F_PERQUEUE_NOTF_COAL is
> > negotiated.
> > \end{enumerate}
> >
> > \subparagraph{RX Notifications}\label{sec:Device Types / Network Device /
> > Device Operation / Control Virtqueue / Notifications Coalescing / RX
> > Notifications}
> > @@ -4531,7 +4557,11 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> > The device will operate as follows:
> >
> > \begin{itemize}
> > -\item The device will count received packets until it accumulates 15, or
> > until 10 usecs elapsed since the first one was received.
> > +\item The device will count received packets until it accumulates 15, or
> > until
> > + 10 usecs elapsed since the first one was received. If additionally
> > + VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated: when \field{rx_qid} is
> > set
> > + to 0, the accumulation was only from the receiveq1; when \field{rx_qid}
> > is
> > + set to 0xFFFF, the accumulation was from all receiveqs.
> > \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}
> >
> > @@ -4546,7 +4576,12 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > Types / Network Device / Devi
> > The device will operate as follows:
> >
> > \begin{itemize}
> > -\item The device will count sent packets until it accumulates 15, or until
> > 10 usecs elapsed since the first one was sent.
> > +\item The device will count sent packets on the transmitq1 until it
> > accumulates 15,
> > + or until 10 usecs elapsed since the first one was sent. If additionally
> > + VIRTIO_NET_F_PERQUEUE_NOTF_COAL is negotiated: when \field{tx_qid} is
> > set
> > + to 0, the accumulation was only from the transmitq1; when
> > \field{tx_qid} is
> > + set to 0xFFFF, the accumulation was from all transmitqs.
> > +
> > \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}
> >
> > --
> > 2.19.1.6.gb485710b
> >
> >
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