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Subject: [PATCH v4] 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>
---
v4:
1. remove dev_stats_num, {rx|tx}_stats_num
2. Use two commands to get the stats of queue pair and dev respectively
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 | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 77 insertions(+), 1 deletion(-)
diff --git a/content.tex b/content.tex
index 7cec1c3..ad8d781 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 */
@@ -3903,7 +3908,8 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
\end{lstlisting}
The \field{class}, \field{command} and command-specific-data are set by the
-driver, and the device sets the \field{ack} byte. There is little it can
+driver, and the device sets the \field{ack} byte and optionally
+\field{command-specific-data-reply}. There is little it can
do except issue a diagnostic if \field{ack} is not
VIRTIO_NET_OK.
@@ -4384,6 +4390,76 @@ \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}.
+
+To get the stats, the following definitions are used:
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_STATS 6
+#define VIRTIO_NET_CTRL_STATS_GET_DEV 0
+#define VIRTIO_NET_CTRL_STATS_GET_QUEUE_PAIR 1
+\end{lstlisting}
+
+The following layout structure are used:
+
+\field{command-specific-data}
+\begin{lstlisting}
+struct virtio_net_ctrl_stats_queue_pair {
+ le64 queue_pair_index;
+}
+\end{lstlisting}
+
+\field{command-specific-data-reply}
+\begin{lstlisting}
+struct virtio_net_ctrl_reply_stats_dev {
+ le64 dev_version; // The number of device version.
+ le64 dev_reset; // The number of device reset.
+}
+
+struct virtio_net_ctrl_reply_stats_queue_pair {
+ le64 queue_pair_index;
+ le64 rx_inter; // The number of interrupts sent by the rx queue.
+ le64 rx_drop; // The number of packets dropped by the rx queue. Contains all kinds of packet loss.
+ le64 rx_drop_overruns; // The number of packets dropped by the rx queue when no more avail desc.
+ le64 rx_csum_bad; // The number of packets with abnormal csum in the rx queue.
+ le64 rx_gso_packets; // The number of gso packets received by rx.
+ le64 rx_gso_bytes; // The number of gso bytes received by rx.
+ le64 rx_oversize_pkts; // The number of oversized packets received by the rx queue.
+ le64 tx_inter; // The number of interrupts sent by the tx queue.
+ le64 tx_drop; // The number of packets dropped by the tx queue. Contains all kinds of packet loss.
+ le64 tx_csum; // The number of packets that completes csum by the device.
+ le64 tx_gso_packets; // The number of gso packets transmitted.
+ le64 tx_gso_bytes; // The number of gso bytes transmitted.
+}
+\end{lstlisting}
+
+All device stats is divided into two categories, one is the stats of the device,
+and the other is the stats of the queue pair. The queue pair stats contains the
+stats of rx and tx.
+
+The command VIRTIO_NET_CTRL_STATS_GET_DEV is used to obtain the stats of the device.
+The command VIRTIO_NET_CTRL_STATS_GET_QUEUE_PAIR is used to obtain the stats of the queue pair.
+
+When the driver uses the command VIRTIO_NET_CTRL_STATS_GET_DEV,
+\field{command-specific-data} MUST be empty. The structure
+\field{virtio_net_ctrl_reply_stats_dev} MUST be used as
+\field{command-specific-data-reply}.
+
+When the driver uses the command VIRTIO_NET_CTRL_STATS_GET_QUEUE_PAIR,
+\field{command-specific-data} MUST be \field{virtio_net_ctrl_stats_queue_pair}. At the same
+time, the structure \field{virtio_net_ctrl_reply_stats_queue_pair} MUST be used as
+\field{command-specific-data-reply}.
+\field{virtio_net_ctrl_stats_queue_pair.queue_pair_index} specify the queue pair
+index of the queue that the driver wants to get stats.
+
+The device MUST set \field{command-specific-data-reply} based on command.
+
+When the command is VIRTIO_NET_CTRL_STATS_GET_QUEUE_PAIR, the device MUST set
+\field{virtio_net_ctrl_reply_stats_queue_pair.queue_pair_index} equal to
+\field{virtio_net_ctrl_stats_queue_pair.queue_pair_index}
+
\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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