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Subject: Re: [virtio-dev] [PATCH v8] virtio-net: support device stats
On Mon, 17 Jan 2022 09:13:41 -0500, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Mon, Jan 17, 2022 at 04:21:50PM +0800, Xuan Zhuo wrote:
> > On Mon, 17 Jan 2022 03:12:20 -0500, Michael S. Tsirkin <mst@redhat.com> wrote:
> > > On Mon, Jan 17, 2022 at 10:14:35AM +0800, Xuan Zhuo wrote:
> > > > On Sat, 15 Jan 2022 13:17:26 -0500, Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > > On Tue, Jan 11, 2022 at 12:01:25PM +0800, Xuan Zhuo wrote:
> > > > > > 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>
> > > > > > Reviewed-by: Jason Wang <jasowang@redhat.com>
> > > > > > ---
> > > > > >
> > > > > > v8:
> > > > > > 1. Modified based on comments by Cornelia Huck
> > > > > >
> > > > > > v7:
> > > > > > 1. add rx_reset, tx_reset
> > > > > > 2. add device normative and dirver normative
> > > > > > 3. add comments for *_packets, *_bytres
> > > > > >
> > > > > > v6:
> > > > > > 1. correct the names and descriptions of some stats items
> > > > > >
> > > > > > v5:
> > > > > > 1. add VIRTIO_NET_CTRL_STATS_GET_CTRL_VQ
> > > > > > 2. more item for virtio_net_ctrl_reply_stats_queue_pair
> > > > > >
> > > > > > 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
> > > > > >
> > > > > > conformance.tex | 2 +
> > > > > > content.tex | 133 +++++++++++++++++++++++++++++++++++++++++++++++-
> > > > > > 2 files changed, 134 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/conformance.tex b/conformance.tex
> > > > > > index 42f8537..950924e 100644
> > > > > > --- a/conformance.tex
> > > > > > +++ b/conformance.tex
> > > > > > @@ -142,6 +142,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
> > > > > > \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode}
> > > > > > \item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State}
> > > > > > \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 / Device stats}
> > > > > > \end{itemize}
> > > > > >
> > > > > > \conformance{\subsection}{Block Driver Conformance}\label{sec:Conformance / Driver Conformance / Block Driver Conformance}
> > > > > > @@ -401,6 +402,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
> > > > > > \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending}
> > > > > > \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode}
> > > > > > \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 / Device stats}
> > > > > > \end{itemize}
> > > > > >
> > > > > > \conformance{\subsection}{Block Device Conformance}\label{sec:Conformance / Device Conformance / Block Device Conformance}
> > > > > > diff --git a/content.tex b/content.tex
> > > > > > index cf20570..fa385e2 100644
> > > > > > --- a/content.tex
> > > > > > +++ b/content.tex
> > > > > > @@ -3092,6 +3092,9 @@ \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.
> > > > > > @@ -3137,6 +3140,7 @@ \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}
> > > > > > @@ -4015,6 +4019,7 @@ \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 */
> > > > >
> > > > > we now need to document which commands include the reply,
> > > > > otherwise reader will be confused.
> > > >
> > > > OK.
> > > >
> > > > >
> > > > > > @@ -4023,7 +4028,8 @@ \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
> > > > >
> > > > > Now "it" refers to device where it used to refer to the driver.
> > > >
> > > > There is little it can except issue a diagnostic if \field{ack} is not VIRTIO_NET_OK.
> > > >
> > > > I don't feel like this has changed or affected anything.
> > >
> > > Well we used to mention just driver. next sentence refers to driver.
> > > now you mention driver and device. what does "it" refer to"? it is now
> > > ambigous.
> > >
> > > > Can you help me change it?
> > >
> > >
> > > Replace "it" with "driver"?
> > >
> > >
> >
> > OK. I see.
> >
> > > >
> > > > >
> > > > > > except issue a diagnostic if \field{ack} is not
> > > > > > VIRTIO_NET_OK.
> > > > > >
> > > > > > @@ -4471,6 +4477,131 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > > > > according to the native endian of the guest rather than
> > > > > > (necessarily when not using the legacy interface) little-endian.
> > > > > >
> > > > > > +\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 in \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_CTRL_VQ 1
> > > > > > +#define VIRTIO_NET_CTRL_STATS_GET_QUEUE_PAIR 2
> > > > > > +\end{lstlisting}
> > > > > > +
> > > > > > +The following layout structures 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_reset; // The number of device resets.
> > > > >
> > > > > while we already have some places using // comments, they
> > > > > are not used consistently. Better to use /* text */ for now.
> > > >
> > > > OK.
> > > >
> > > > >
> > > > > > +}
> > > > >
> > > > >
> > > > >
> > > > > I am still worrying about this one. I think it's a bit vague.
> > > > > Some types of reset will zero this counter, others will not.
> > > > > Also, this looks more like a generic capability than anything
> > > > > specific to net. And this raises questions about .
> > > >
> > > >
> > > > I think, I should define that the device will not set this variable to 0 during
> > > > reset.
> > >
> > > again there's reset and there's reset. if you power cycle
> > > the system is device expected to retain this? the bus?
> > > what about pcie link level reset? etc
> >
> > So it's wrong to record statistics in reset, right?
>
> depends on the kind of reset. for some kinds its outright impossible.
> it is certainly easier not to worry about this and just reset
> everything.
OK, I'll delete the dev_reset stat.
>
> > >
> > > > The purpose of adding this is to count the number of times the user deletes/adds
> > > > the network card. The virtio-net device may be deleted/added by the user
> > > > multiple times,
> > >
> > > I don't get it really ... deletes/adds card how?
> >
> > For virtio-net, "ip link del eth1" is not supported. I don't know why.
>
> because what it does is add a virtual link, and virtio does not
> support vlan offloading atm?
>
> so I would maybe add vlan offloading instead ;)
You mean to add vlan-related statistics to the dev category, right?
>
> > I usually
> > use this command.
> >
> > echo virtio1 > /sys/class/net/eth1/device/driver/unbind
>
> and that unbinds the driver from the device
>
Yes, I do this often to simulate a drive reset.
>
> > >
> > > > and this is reflected in the device layer as the number of
> > > > resets.
> > >
> > >
> > > Well your text does not explain it exactly.
> > >
> > >
> > > > >
> > > > >
> > > > >
> > > > > > +
> > > > > > +struct virtio_net_ctrl_reply_stats_cvq {
> > > > > > + le64 request_num; // The number of requests.
> > > > >
> > > > > We call them commands elsewhere. It is however unclear whether
> > > > > the request for the stats itself is included in the counter.
> > > > > Also, do these counters reset on device reset? I would
> > > > > assume so but given dev_reset does not reset it's hard to be
> > > > > sure.
> > > >
> > > >
> > > > I will change request -> command.
> > > >
> > > > We should really define that the device should not reset these statistics during
> > > > reset
> > >
> > > I don't think I agree. new device - new stats.. physical cards seem to
> > > reset these things.
> >
> >
> > ok, let's confirm this first. After reset, all statistics will start from 0
> > again.
> >
> >
> > >
> > > >
> > > > >
> > > > > > + le64 ok_num; // The number of ok acks.
> > > > > > + le64 err_num; // The number of err acks.
> > > > >
> > > > > A bit more precise pls: e.g. "the number of commands where ack was
> > > > > VIRTIO_NET_OK"?
> > > >
> > > >
> > > > OK
> > > >
> > > > >
> > > > >
> > > > > > +
> > > > > > + le64 req_rx_promisc; // The number of requests with command VIRTIO_NET_CTRL_RX_PROMISC.
> > > > > > + le64 req_rx_allmulti; // The number of requests with command VIRTIO_NET_CTRL_RX_ALLMULTI.
> > > > > > + le64 req_rx_alluni; // The number of requests with command VIRTIO_NET_CTRL_RX_ALLUNI.
> > > > > > + le64 req_rx_nomulti; // The number of requests with command VIRTIO_NET_CTRL_RX_NOMULTI.
> > > > > > + le64 req_rx_nouni; // The number of requests with command VIRTIO_NET_CTRL_RX_NOUNI.
> > > > > > + le64 req_rx_nobcast; // The number of requests with command VIRTIO_NET_CTRL_RX_NOBCAST.
> > > > > > + le64 req_mac_table_set; // The number of requests with command VIRTIO_NET_CTRL_MAC_TABLE_SET.
> > > > > > + le64 req_mac_addr_set; // The number of requests with command VIRTIO_NET_CTRL_MAC_ADDR_SET.
> > > > > > + le64 req_vlan_add; // The number of requests with command VIRTIO_NET_CTRL_VLAN_ADD.
> > > > > > + le64 req_vlan_del; // The number of requests with command VIRTIO_NET_CTRL_VLAN_DEL.
> > > > > > + le64 req_announce_ack; // The number of requests with command VIRTIO_NET_CTRL_ANNOUNCE_ACK.
> > > > > > + le64 req_mq_vq_pairs_set; // The number of requests with command VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET.
> > > > > > + le64 req_mq_rss_config; // The number of requests with command VIRTIO_NET_CTRL_MQ_RSS_CONFIG.
> > > > > > + le64 req_mq_hash_config; // The number of requests with command VIRTIO_NET_CTRL_MQ_HASH_CONFIG.
> > > > > > + le64 req_guest_offloads_set; // The number of requests with command VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET.
> > > > > > +}
> > > > >
> > > > >
> > > > > I just had an idea:
> > > > > how about the query passes in the command we are debugging instead?
> > > > > this way we do not need to extend this each time.
> > > > >
> > > >
> > > > Do you mean command-specific-data uses a structure like this:
> > > >
> > > > {
> > > > le64 class;
> > > > le64 command;
> > > > }
> > > >
> > > > This is indeed a really great idea.
> > >
> > >
> > > can't say what you mean exactly here. just pass the command
> > > you want stats about to the card, is my idea.
> >
> > I mean pass the desired command (class, command) to the device in
> > command-specific-data.
> >
> > Include only a num in the command-specific-data-reply as a response from the
> > device.
> >
> > struct {
> > le64 num;
> > }
> >
> >
> > >
> > > >
> > > > >
> > > > >
> > > > >
> > > > > > +
> > > > > > +struct virtio_net_ctrl_reply_stats_queue_pair {
> > > > > > + /* rx stats */
> > > > > > + le64 rx_packets; // The number of packets recived by device, including the dropped packets by device.
> > > > > > + le64 rx_bytes; // The number of bytes recived by device, including the dropped packets by device.
> > > > >
> > > > > typos: received
> > > > >
> > > > >
> > > > > > +
> > > > > > + le64 rx_notification; // The number of notifications from driver.
> > > > > > + le64 rx_interrupt; // The number of interrupts generated by device.
> > > > > > +
> > > > > > + le64 rx_drop; // The number of packets dropped by the rx queue. Contains all kinds of packet drop.
> > > > > > + le64 rx_drop_overruns; // The number of packets dropped by the rx queue when no more descriptors were available.
> > > > > > + le64 rx_drop_oversize; // The number of oversized packets received by the rx queue.
> > > > >
> > > > > What does oversized mean in this context? does it apply to
> > > > > mergeable buffers?
> > > >
> > > > For mergeable buffers this statistic is meaningless.
> > >
> > > something to mention then. or should we bother at all?
> >
> > sorry i didn't understand.
>
> is this a common thing? why do we need this counter?
For small mode, this statistic is necessary.
>
> > >
> > > > >
> > > > > > +
> > > > > > + le64 rx_csum_valid; // The number of packets with VIRTIO_NET_HDR_F_DATA_VALID.
> > > > > > + le64 rx_csum_partial; // The number of packets with VIRTIO_NET_HDR_F_NEEDS_CSUM.
> > > > > > + le64 rx_csum_bad; // The number of packets with abnormal csum.
> > > > > > + le64 rx_csum_none; // The number of packets without hardware csum.
> > > > >
> > > > > I assume they are only incremented with VIRTIO_NET_F_GUEST_CSUM?
> > > >
> > > > Yes
> > > >
> > > > >
> > > > > > +
> > > > > > + le64 rx_gso_packets; // The number of gso packets received by rx.
> > > > >
> > > > > let's spell it out: I think this means any packet
> > > > > put into VQ and with gso_type != VIRTIO_NET_HDR_GSO_NONE
> > > >
> > > > Yes
> > > >
> > > >
> > > > >
> > > > > > + le64 rx_gso_bytes; // The number of gso bytes received by rx.
> > > > >
> > > > > this one is a bit vague: I assume these are bytes written into the RX VQ buffers?
> > > > > the difference is that multiple packets are combined into a
> > > > > single gso packet.
> > > > > and does this include the virtio net header?
> > > >
> > > > I think all *_bytes statistics do not include virtio net header, the packet
> > > > bytes we care about does not include virtio net header.
> > > >
> > > > Multiple packets are combined into one, and some network headers, such as
> > > > ip/tcp, etc., are also removed. The final count is the bytes that are finalized
> > > > to the RV VQ buffers.
> > >
> > > sounds quite tricky to document. but go ahead and try if you like.
> > >
> > >
> > > >
> > > > >
> > > > > > + le64 rx_reset; // The number of queue resets.
> > > > > > +
> > > > > > + /* tx stats */
> > > > > > + le64 tx_packets; // The number of packets sent by device, excluding the dropped packets by device.
> > > > > > + le64 tx_bytes; // The number of bytes sent by device, excluding the dropped packets by device.
> > > > >
> > > > > same question: are we talking about bytes sent by device? or
> > > > > received from guest for transmission?
> > > >
> > > > The number of bytes sent by device.
> > >
> > > not symmetrical with rx then in case of gso.
> > >
> > > > >
> > > > > > +
> > > > > > + le64 tx_notification; // The number of notifications from driver.
> > > > > > + le64 tx_interrupt; // The number of interrupts generated by device.
> > > > > > +
> > > > > > + le64 tx_drop; // The number of packets dropped by the tx queue. Contains all kinds of packet drop.
> > > > > > + le64 tx_drop_desc_err; // The number of packets dropped when the descriptor is in an error state.
> > > > >
> > > > > what is a descriptor in error state?
> > > >
> > > > such as len == 0.
> > >
> > > We never really documented what does it do.
> > > maybe malformed packets would be better?
> > > buffer too short?
> > > something more specific.
> >
> > OK.
> >
> > >
> > > >
> > > > >
> > > > > > +
> > > > > > + le64 tx_csum_none; // The number of packets that doesn't require hardware csum.
> > > > > > + le64 tx_csum_partial; // The number of packets that requires hardware csum.
> > > > > > +
> > > > > > + le64 tx_gso_packets; // The number of gso packets transmitted.
> > > > > > + le64 tx_gso_bytes; // The number of gso bytes transmitted.
> > > > >
> > > > > point is, gso packets are not transmitted. they are received from
> > > > > guest. is this what this means?
> > > >
> > > > Yes.
> > > >
> > > > > gso bytes probably somehow
> > > > > means bytes in gso packets, but again this is a bit vague.
> > > >
> > > > It should be defined, I think it should be defined as the number of bytes from
> > > > the guest.
> > > >
> > >
> > > above you said bytes sent.
> >
> > I mean, all about GSO are statistics based on big packets. So here is the
> > package from Guest, and rx is the package passed to Guest.
>
> it's a subtle distinction that we need to make.
I will make this clear in the next version.
Thanks
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