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Subject: [PATCH v3] virtio-net: support device stats
This patch allows the driver to obtain some statistics from the device. In the back-end implementation, we can count a lot of such information, which can be used for debugging and judging the running status of the back-end. We hope to directly display it to the user through ethtool. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- v3 changes: 1. add dev_version 2. use queue_pair_index replace rx_num, tx_num 3. Explain the processing when the device and driver support different numbers of stats content.tex | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) diff --git a/content.tex b/content.tex index 7cec1c3..2e45a55 100644 --- a/content.tex +++ b/content.tex @@ -2972,6 +2972,9 @@ \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_CTRL_STATS(55)] Device can provide device-level statistics + to the driver through the control channel. + \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. @@ -3017,6 +3020,7 @@ \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_CTRL_STATS] 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} @@ -3895,6 +3899,7 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi u8 command; u8 command-specific-data[]; u8 ack; + u8 command-specific-data-reply[]; }; /* ack values */ @@ -3906,6 +3911,9 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi driver, and the device sets the \field{ack} byte. There is little it can do except issue a diagnostic if \field{ack} is not VIRTIO_NET_OK. +\field{command-specific-data-reply} is alloced by driver, then pass to device. +It is filled by the device. It is optional. Some commands need to get some +information from the device. \paragraph{Packet Receive Filtering}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Packet Receive Filtering} \label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting Promiscuous Mode}%old label for latexdiff @@ -4384,6 +4392,113 @@ \subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing}. +\paragraph{Device stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device stats} + +If the VIRTIO_NET_F_CTRL_STATS feature is negotiated, the driver can +get device stats from the device by \field{command-specific-data-reply}. + +\subparagraph{Device stats keys}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device stats keys / Device stats keys} + +The keys of the device stats are defined as follows. When the device fills in +\field{command-specific-data-reply}, it MUST be written in the following order. +Subsequent newly added keys MUST be added at the end of each category. +These keys will eventually be shown to the user. + +All stats are divided into three categories: + +\begin{itemize} + \item dev stats: the stats of the device + \begin{itemize} + \item dev_version: The number of device version. + \item dev_reset: The number of device reset. + \end{itemize} + + \item rx stats: the stats of the rx queue + \begin{itemize} + \item rx[N]_inter: The number of interrupts sent by the rx queue. + \item rx[N]_drop: The number of packets dropped by the rx queue. Contains all kinds of packet loss. + \item rx[N]_drop_overruns: The number of packets dropped by the rx queue when no more avail desc. + \item rx[N]_csum_bad: The number of packets with abnormal csum in the rx queue. + \item rx[N]_gso_packets: The number of gso packets received by rx. + \item rx[N]_gso_bytes: The number of gso bytes received by rx. + \item rx[N]_oversize_pkts: The number of oversized packets received by the rx queue. + \end{itemize} + + \item tx stats: the stats of the tx queue + \begin{itemize} + \item tx[N]_inter: The number of interrupts sent by the tx queue. + \item tx[N]_drop: The number of packets dropped by the tx queue. Contains all kinds of packet loss. + \item tx[N]_csum: The number of packets that completes csum by the device. + \item tx[N]_gso_packets: The number of gso packets transmitted. + \item tx[N]_gso_bytes: The number of gso bytes transmitted. + \end{itemize} +\end{itemize} + +\subparagraph{Device stats get}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device stats keys / Device stats get} + +To get the stats, the following definitions are used: +\begin{lstlisting} +#define VIRTIO_NET_CTRL_STATS 6 +#define VIRTIO_NET_CTRL_STATS_GET 0 +\end{lstlisting} + +The following layout structure are used: + +\field{command-specific-data} +\begin{lstlisting} +le64 queue_pair_index +le64 dev_stats_num; +le64 rx_stats_num; +le64 tx_stats_num; +\end{lstlisting} + +\field{command-specific-data-reply} +\begin{lstlisting} +le64 queue_pair_index +le64 dev_stats_num; +le64 rx_stats_num; +le64 tx_stats_num; +le64 dev_stats[dev_stats_num]; +le64 rx_stats[rx_stats_num]; +le64 tx_stats[tx_stats_num]; +\end{lstlisting} + +The command VIRTIO_NET_CTRL_STATS_GET is used to obtain this information. + +Regarding the variables in \field{command-specific-data}: +\begin{itemize} + \item \field{queue_pair_index}: Specify the queue pair index of the queue that the driver wants to get stats. + \item \field{dev_stats_num}: Indicates the number of dev stats supported by the driver. + \item \field{rx_stats_num}: Indicates the number of stats information the driver wants for rx queue. + \item \field{tx_stats_num}: Indicates the number of stats information the driver wants for tx queue. +\end{itemize} + +Regarding the variables in \field{command-specific-data-reply}: +\begin{itemize} + \item All variables of \field{command-specific-data-reply} are set by the device. + \item \field{queue_pair_index} MUST be equal to the variable with the same name in \field{command-specific-data}. + \item These variables(\field{dev_stats_num}, \field{rx_stats_num}, \field{tx_stats_num}) MUST be + less than or equal to the variables with the same name in \field{command-specific-data}. + These values indicate the amount of stats actually filled in. + \item \field{command-specific-data-reply} is meaningful only when \field{ack} is equal to VIRTIO_NET_OK. +\end{itemize} + +The variables \field{dev_stats_num}, \field{rx_stats_num}, \field{tx_stats_num} in \field{command-specific-data} +specify which stats the driver wants to get, but in fact the device may support +more or fewer stats. + +If the actual number of stats supported by the device is equal to or less than +the number that the driver wants to obtain, then the device MUST write all the +stats to the corresponding position of \field{command-specific-data-reply}. + +And if the number of stats actually supported by the device is more than the +driver requires, then the device MUST only write the number supported by the +driver. + +If the some of the variables \field{dev_stats_num}, \field{rx_stats_num}, \field{tx_stats_num} in \field{command-specific-data} are 0, +that means that the driver does not want to obtain this type of stats, +then the device MUST set the same name field in \field{command-specific-data-reply} to 0, and skip this type of stats. + \section{Block Device}\label{sec:Device Types / Block Device} The virtio block device is a simple virtual block device (ie. -- 2.31.0
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