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Subject: Re: [PATCH v14] virtio-net: support device stats
On Monday, 2023-07-31 at 15:27:22 +08, Xuan Zhuo wrote: > This patch allows the driver to obtain some statistics from the device. > > In the device implementation, we can count a lot of such information, > which can be used for debugging and judging the running status of the > device. We hope to directly display it to the user through ethtool. > > To get stats atomically, try to get stats for all queue pairs in one > command. > > If the feature is negotiated, the device must support all the stats > listed in this commit. If we want add new stats in future, one new > feature should be introduced. Did you consider a query mechanism to avoid the need for a proliferation of feature bits? > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > Suggested-by: Michael S. Tsirkin <mst@redhat.com> > --- > > v14: > * introduce supported_stats to config space > * add header(vq_index, size, type) to each reply stats > * add ref to the tx GSO > > device-types/net/description.tex | 365 +++++++++++++++++++++++- > device-types/net/device-conformance.tex | 1 + > device-types/net/driver-conformance.tex | 1 + > 3 files changed, 364 insertions(+), 3 deletions(-) > > diff --git a/device-types/net/description.tex b/device-types/net/description.tex > index 76585b0..fd7160a 100644 > --- a/device-types/net/description.tex > +++ b/device-types/net/description.tex > @@ -88,6 +88,9 @@ \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_DEVICE_STATS(50)] Device can provide device-level statistics > + to the driver through the control channel. > + > \item[VIRTIO_NET_F_HASH_TUNNEL(51)] Device supports inner header hash for encapsulated packets. > > \item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports virtqueue notification coalescing. > @@ -1156,6 +1159,7 @@ \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 */ > @@ -1164,9 +1168,11 @@ \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 > -do except issue a diagnostic if \field{ack} is not > -VIRTIO_NET_OK. > +driver, and the device sets the \field{ack} byte and optionally > +\field{command-specific-data-reply}. There is little the driver can > +do except issue a diagnostic if \field{ack} is not VIRTIO_NET_OK. > + > +The command VIRTIO_NET_CTRL_STATS_GET contains \field{command-specific-data-reply}. > > \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 > @@ -1805,6 +1811,359 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > Upon reset, a device MUST initialize all coalescing parameters to 0. > > +\paragraph{Device Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats} "Stats" is an abbreviation - in the prose it would be better to use "statistics" consistently. > + > +If the VIRTIO_NET_F_DEVICE_STATS feature is negotiated, the driver can obtain > +device stats from the device by using the following command. > + > +Different types of virtqueues have different stats. The stats of the receiveq > +are different from those of the transmitq. > + > +The stats of a certain type of virtqueue are also divided into multiple types > +because different types require different features. This enables the expansion > +of new stats. > + > +At one time, the driver can obtain the stats of one or multiple virtqueues. > +Additionally, the driver can obtain multiple type stats of each virtqueue. > + > +\begin{lstlisting} > +#define VIRTIO_NET_CTRL_STATS 7 > +#define VIRTIO_NET_CTRL_STATS_GET 0 > +\end{lstlisting} > + > +To obtain device stats, use the VIRTIO_NET_CTRL_STATS_GET command with the > +\field{command-specific-data} containing the virtio_net_ctrl_queue_stats > +structure. The result is returned in the \field{command-specific-data-reply}. > + > +The following structure is used in \field{command-specific-data}: > +\begin{lstlisting} > +struct virtio_net_ctrl_queue_stats { > + struct { > + u16 vq_index; > + u48 padding; u8 padding[6] ? Not sure that u48 is used anywhere else. > + > +#define VIRTIO_NET_STATS_TYPE_CVQ (1 << 0) > + > +#define VIRTIO_NET_STATS_TYPE_RX_BASIC (1 << 0) > +#define VIRTIO_NET_STATS_TYPE_RX_CSUM (1 << 1) > +#define VIRTIO_NET_STATS_TYPE_RX_GSO (1 << 2) > + > +#define VIRTIO_NET_STATS_TYPE_TX_BASIC (1 << 0) > +#define VIRTIO_NET_STATS_TYPE_TX_CSUM (1 << 1) > +#define VIRTIO_NET_STATS_TYPE_TX_GSO (1 << 2) > + > + u64 types; > + } stats[]; > +}; > +\end{lstlisting} > + > +The following structures are used in \field{command-specific-data-reply}: > +\begin{lstlisting} > +struct virtio_net_stats_cvq { > + le64 command_num; > + le64 ok_num; > +}; > + > +struct virtio_net_stats_rx_basic { > + le64 rx_packets; > + le64 rx_bytes; > + > + le64 rx_notification; > + le64 rx_interrupt; > + > + le64 rx_drop; > + le64 rx_drop_overruns; > + le64 rx_drop_busy; > +}; > + > +struct virtio_net_stats_rx_csum { > + le64 rx_csum_valid; > + le64 rx_needs_csum; > + le64 rx_csum_bad; > + le64 rx_csum_none; > +}; > + > +struct virtio_net_stats_rx_gso { > + le64 rx_gso_packets; > + le64 rx_gso_bytes; > + le64 rx_gso_packets_coalesced; > + le64 rx_gso_bytes_coalesced; > + le64 rx_gso_segments; > + le64 rx_gso_segments_bytes; > +}; > + > +struct virtio_net_stats_tx_basic { > + le64 tx_packets; > + le64 tx_bytes; > + > + le64 tx_notification; > + le64 tx_interrupt; > + > + le64 tx_drop; > + le64 tx_drop_malformed; > + > + le64 tx_drop_busy; > +}; > + > +struct virtio_net_stats_tx_csum { > + le64 tx_csum_none; > + le64 tx_needs_csum; > +}; > + > +struct virtio_net_stats_tx_gso { > + le64 tx_gso_packets; > + le64 tx_gso_bytes; > + le64 tx_gso_packets_split; > + le64 tx_gso_bytes_split; > + le64 tx_gso_segments; > + le64 tx_gso_segments_bytes; > +}; > + > +\end{lstlisting} > + > +\begin{description} > + \item [vq_index] > + The index of the virtqueue to obtain the stats. > + > + \item [types] > + This is a bitmask of the types of stats to be obtained. Therefore, a > + \field{struct stats} inside virtio_net_ctrl_queue_stats may instruct > + multiple stats replies for the virtqueue. > +\end{description} > + > +\subparagraph{Controlq Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Controlq Stats} > + > +The structure corresponding to the controlq stats is virtio_net_stats_cvq. > + > +\begin{description} > + \item [command_num] > + The number of commands including the current command. > + > + \item [ok_num] > + The number of commands (including the current command) where the ack was VIRTIO_NET_OK. > +\end{description} > + > + > +\subparagraph{Receiveq Basic Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Receiveq Basic Stats} > + > +The structure corresponding to the receiveq basic stats is virtio_net_stats_rx_basic. > + > +Receiveq basic stats doesn't require any feature. As long as the device supports s/doesn't/does not/ > +VIRTIO_NET_F_DEVICE_STATS, the following are the receiveq basic stats. > + > +The packets described below are all steered to a specific virtqueue. "steered" seems like a loaded term. Perhaps "The packets described below were all presented on the specified virtqueue."? > +\begin{description} > + \item [rx_packets] > + This is the number of packets received by the device (not the packets > + passed to the guest). The count includes the packets dropped by the > + device. > + > + \item [rx_bytes] > + This is the bytes of packets received by the device (not the packets > + passed to the guest). The count includes the packets dropped by the > + device. > + > + \item [rx_notification] > + The number of driver notifications received by device for this receiveq. > + > + \item [rx_interrupt] > + The number of device interrupts for this receiveq. > + > + \item [rx_drop] > + This is the number of packets dropped by the device. The count includes > + all types of packets dropped by the device. > + > + \item [rx_drop_overruns] > + This is the number of packets dropped by the device when no more > + descriptors were available. > + > + \item [rx_drop_busy] > + This is the number of packets dropped by the device when the device is > + busy. > + > +\end{description} > + > +\subparagraph{Transmitq Basic Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Transmitq Basic Stats} > + > +The structure corresponding to VIRTIO_NET_STATS_TYPE_TX_BASIC is virtio_net_stats_tx_basic. > + > +Transmitq basic stats doesn't require any feature. As long as the device supports > +VIRTIO_NET_F_DEVICE_STATS, the following are the transmitq basic stats. > + > +The packets described below are all from a specific virtqueue. > +\begin{description} > + \item [tx_packets] > + This is the number of packets sent by the device (not the packets > + got from the driver). > + > + \item [tx_bytes] > + This is the bytes of packets sent by the device (not the packets > + got from the driver). > + > + \item [tx_notification] > + The number of driver notifications for this transmitq. > + > + \item [tx_interrupt] > + The number of device interrupts for this transmitq. > + > + \item [tx_drop] > + The number of packets dropped by the device. The count includes all > + types of packets dropped by the device. > + > + \item [tx_drop_malformed] > + The number of packets dropped by the device, when the descriptor is in > + an error state. For example, the buffer is too short. > + > + \item [tx_drop_busy] > + The number of packets dropped by the device, when the device is busy. > + > +\end{description} > + > +\subparagraph{Receiveq CSUM Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Receiveq CSUM Stats} > + > +The structure corresponding to VIRTIO_NET_STATS_TYPE_RX_CSUM is virtio_net_stats_rx_csum. > + > +Only after the VIRTIO_NET_F_GUEST_CSUM is negotiated, the receiveq csum stats > +can be obtained. > + > +The packets described below are all steered to a specific virtqueue. > +\begin{description} > + \item [rx_csum_valid] > + The number of packets with VIRTIO_NET_HDR_F_DATA_VALID. > + > + \item [rx_needs_csum] > + The number of packets with VIRTIO_NET_HDR_F_NEEDS_CSUM. > + > + \item [rx_csum_bad] > + The number of packets with abnormal csum. > + > + \item [rx_csum_none] > + The number of packets without hardware csum. The packet here refers to > + the non-TCP/UDP packet that the backend cannot recognize. > + > +\end{description} > + > +\subparagraph{Transmitq CSUM Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Transmitq CSUM Stats} > + > +The structure corresponding to VIRTIO_NET_STATS_TYPE_TX_CSUM is virtio_net_stats_tx_csum. > + > +Only after the VIRTIO_NET_F_CSUM is negotiated, the transmitq csum stats can be > +obtained. > + > +The following are the transmitq csum stats: > + > +The packets described below are all from a specific virtqueue. > +\begin{description} > + \item [tx_csum_none] > + The number of packets that didn't require hardware csum. > + > + \item [tx_needs_csum] > + The number of packets that required hardware csum. > + > +\end{description} > + > +\subparagraph{Receiveq GSO Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Receiveq GSO Stats} > + > +The structure corresponding to VIRTIO_NET_STATS_TYPE_RX_GSO is virtio_net_stats_rx_gso. > + > +If one or more of the VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, or > +VIRTIO_NET_F_GUEST_UFO have been negotiated, the receiveq GSO stats can be > +obtained. > + > +GSO packets refer to packets passed by the device to the driver where > +\field{gso_type} is not VIRTIO_NET_HDR_GSO_NONE. > + > +The packets described below are all steered to a specific virtqueue. > +\begin{description} > + \item [rx_gso_packets] > + The number of the GSO packets received by device. > + > + \item [rx_gso_bytes] > + The bytes of the GSO packets received by device. > + > + \item [rx_gso_packets_coalesced] > + The number of the GSO packets coalesced by device. > + > + \item [rx_gso_bytes_coalesced] > + The bytes of the GSO packets coalesced by device. > + > + \item [rx_gso_segments] > + The number of the segments that make up GSO packets. > + > + \item [rx_gso_segments_bytes] > + The bytes of the segments that make up GSO packets. > + > +\end{description} > + > +\subparagraph{Transmitq GSO Stats}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats / Transmitq GSO Stats} > + > +The structure corresponding to VIRTIO_NET_STATS_TYPE_TX_GSO is virtio_net_stats_tx_gso. > + > +If one or more of the VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_TSO6, > +VIRTIO_NET_F_HOST_USO or VIRTIO_NET_F_HOST_UFO options have > +been negotiated, the transmitq GSO stats can be obtained. > + > +GSO packets refer to packets passed by the driver to the device where > +\field{gso_type} is not VIRTIO_NET_HDR_GSO_NONE. > + > +The packets described below are all from a specific virtqueue. > +\begin{description} > + \item [tx_gso_packets] > + The number of the GSO packets sent by device that are not split to small > + packets. > + > + \item [tx_gso_bytes] > + The bytes of the GSO packets sent by device that are not split to small > + packets. > + > + \item [tx_gso_packets_split] > + The number of the GSO packets that been split to small packets. > + > + \item [tx_gso_bytes_split] > + The bytes of the GSO packets that been split to small packets. > + > + \item [tx_gso_segments] > + The number of segments split from the GSO packets. > + > + \item [tx_gso_segments_bytes] > + The bytes of segments split from the GSO packets. > +\end{description} > + > +\devicenormative{\subparagraph}{Device Stats}{Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats} > + > +If virtio_net_ctrl_queue_stats is incorrect (such as the following), the device > +MUST set \field{ack} to VIRTIO_NET_ERR. Even if there is only one error, > +the device MUST fail the entire command. > +\begin{itemize} > + \item \field{vq_index} exceeds the queue range. > + \item \field{types} contains unknown types. > + \item The type of vq does not match \field{types}. E.g. the driver tries to query > + receiveq stats by the index of a transmitq. How would a device detect this, given that the bits used to express the statistics type overlap? If I ask for TX_CSUM on an RX queue, I'm going to get the RX_CSUM stats and the device cannot be aware of the discrepancy. This might be better as: \item One or more of the bits present in \field{types} is not valid for the specified virtqueue. > + \item The feature corresponding to the specified \field{types} was not negotiated. > + \item The size of the buffer allocated by the driver for \field{command-specific-data-reply} > + is less than the total size of the stats specialed by > + \field{virtio_net_ctrl_queue_stats}. > +\end{itemize} > + > +The device MUST write the requested stats structures in > +\field{command-specific-data-reply} in the order specified by the structure > +virtio_net_ctrl_queue_stats. If the \field{types} instructs multiple stats, the > +replies order by the type value from small to large. How are the multiple replies padded? "There is no additional padding between structures." would be sufficient, I think. > + > +\drivernormative{\subparagraph}{Device Stats}{Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats} > + > +When a driver tries to obtain a certain stats, it MUST confirm that the relevant > +features are negotiated. > + > +\field{types} in struct virtio_net_ctrl_queue_stats MUST correspond to the vq > +specified by \field{vq_index}. > + > +The \field{command-specific-data-reply} buffer allocated by the driver MUST be > +able to hold all the stats specified by virtio_net_ctrl_queue_stats. > + > +When the driver reads the replies, it MUST read > +\field{command-specific-data-reply} one by one based on the \field{types}. Not clear why this is here? The driver should be able to consume the result however it chooses. > + > \subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device > Types / Network Device / Legacy Interface: Framing Requirements} > > diff --git a/device-types/net/device-conformance.tex b/device-types/net/device-conformance.tex > index f88f48b..a0c63d6 100644 > --- a/device-types/net/device-conformance.tex > +++ b/device-types/net/device-conformance.tex > @@ -15,4 +15,5 @@ > \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS processing} > \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Notifications Coalescing} > \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash} > +\item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats} > \end{itemize} > diff --git a/device-types/net/driver-conformance.tex b/device-types/net/driver-conformance.tex > index 9d853d9..2f1c674 100644 > --- a/device-types/net/driver-conformance.tex > +++ b/device-types/net/driver-conformance.tex > @@ -15,4 +15,5 @@ > \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) } > \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Notifications Coalescing} > \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Inner Header Hash} > +\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Device Stats} > \end{itemize} > -- > 2.32.0.3.g01195cf9f > > 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: virtio-comment-subscribe@lists.oasis-open.org > Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > List help: virtio-comment-help@lists.oasis-open.org > 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/ -- Tonight I'm gonna bury that horse in the ground.
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