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Subject: [PATCH] Introduction of Virtio Network device interrupt coalescing feature
Control a network device interrupt coalescing parameters using the control virtqueue. A new control class was added: VIRTIO_NET_CTRL_INTR_COAL. This class provides 2 commands: - VIRTIO_NET_CTRL_INTR_COAL_USECS_SET: Ask the network device to change the rx-usecs and tx-usecs parameters. rx-usecs - Time to delay an RX interrupt after packet arrival in microseconds. tx-usecs - Time to delay a TX interrupt after a sending a packet in microseconds. - VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET: Ask the network device to change the rx-max-frames and tx-max-frames parameters. rx-max-frames - Number of packets to delay an RX interrupt after packet arrival. tx-max-frames - Number of packets to delay a TX interrupt after sending a packet. Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com> --- content.tex | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/content.tex b/content.tex index 7508dd1..a70cb27 100644 --- a/content.tex +++ b/content.tex @@ -3084,6 +3084,8 @@ \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_INTR_COAL(55)] Device supports interrupt coalescing. + \item[VIRTIO_NET_F_HOST_USO (56)] Device can receive USO packets. Unlike UFO (fragmenting the packet) the USO splits large UDP packet to several segments when each of these smaller packets has UDP header. @@ -3129,6 +3131,7 @@ \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device \item[VIRTIO_NET_F_GUEST_ANNOUNCE] Requires VIRTIO_NET_F_CTRL_VQ. \item[VIRTIO_NET_F_MQ] Requires VIRTIO_NET_F_CTRL_VQ. \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ. +\item[VIRTIO_NET_F_INTR_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. \end{description} @@ -4464,6 +4467,44 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi (necessarily when not using the legacy interface) little-endian. +\paragraph{Interrupt Coalescing}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Interrupt Coalescing} + +If the VIRTIO_NET_F_INTR_COAL feature is negotiated, the driver can +send control commands for dynamically changing the coalescing parameters. + +\begin{lstlisting} +struct virtio_net_ctrl_coal_usec { + le32 tx_usecs; + le32 rx_usecs; +}; + +struct virtio_net_ctrl_coal_frames { + le32 tx_frames_max; + le32 rx_frames_max; +}; + +#define VIRTIO_NET_CTRL_INTR_COAL 6 + #define VIRTIO_NET_CTRL_INTR_COAL_USECS_SET 0 + #define VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET 1 +\end{lstlisting} + +The class VIRTIO_NET_CTRL_INTR_COAL has 2 commands: +\begin{itemize} +\item VIRTIO_NET_CTRL_INTR_COAL_USECS_SET: set the rx-usecs (time to delay an RX interrupt after packet arrival in microseconds) and tx-usecs (time to delay a TX interrupt after a sending a packet in microseconds) parameters. +\item VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET: set the rx-max-frames (number of packets to delay an RX interrupt after packet arrival) and tx-max-frames (number of packets to delay a TX interrupt after sending a packet) parameters. +\end{itemize} + +\drivernormative{\subparagraph}{Interrupt Coalescing}{Device Types / Network Device / Device Operation / Control Virtqueue / Interrupt Coalescing} + + +A driver MUST NOT send to the device VIRTIO_NET_CTRL_INTR_COAL commands if the VIRTIO_NET_F_INTR_COAL feature +has not been negotiated. + +\devicenormative{\subparagraph}{Interrupt Coalescing}{Device Types / Network Device / Device Operation / Control Virtqueue / Interrupt Coalescing} + +A device SHOULD respond to the VIRTIO_NET_CTRL_INTR_COAL commands with VIRTIO_NET_ERR if was not able to change the parameters. + + \subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device Types / Network Device / Legacy Interface: Framing Requirements} -- 2.32.0
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