From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: References: <20230222140632.10253-1-hengqi@linux.alibaba.com> <3e0d0bd0-b3e8-1616-7fd6-8a4a5a35e6db@linux.alibaba.com> <20230223081813-mutt-send-email-mst@kernel.org> From: David Edmondson Date: Thu, 23 Feb 2023 16:34:29 +0000 In-reply-to: <20230223081813-mutt-send-email-mst@kernel.org> Message-ID: MIME-Version: 1.0 Subject: [virtio-comment] Re: [virtio-dev] Re: [virtio-comment] Re: [PATCH v7] virtio-net: support the virtqueue coalescing moderation Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable To: "Michael S. Tsirkin" Cc: Heng Qi , Parav Pandit , Alvaro Karsz , Jason Wang , Xuan Zhuo , Cornelia Huck , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org List-ID: On Thursday, 2023-02-23 at 08:20:34 -05, Michael S. Tsirkin wrote: > On Thu, Feb 23, 2023 at 11:43:29AM +0000, David Edmondson wrote: >>=20 >> On Thursday, 2023-02-23 at 18:52:14 +08, Heng Qi wrote: >> > Hi, David. >> > >> > =E5=9C=A8 2023/2/23 =E4=B8=8B=E5=8D=886:05, David Edmondson =E5=86=99= =E9=81=93: >> >> On Wednesday, 2023-02-22 at 22:06:32 +08, Heng Qi wrote: >> >>> Currently, coalescing parameters are grouped for all transmit and re= ceive >> >>> virtqueues. This patch supports setting or getting the parameters fo= r a >> >>> specified virtqueue, and a typical application of this function is n= etdim[1]. >> >>> >> >>> When the traffic between virtqueues is unbalanced, for example, one = virtqueue >> >>> is busy and another virtqueue is idle, then it will be very useful t= o >> >>> control coalescing parameters at the virtqueue granularity. >> >>> >> >>> [1] https://docs.kernel.org/networking/net_dim.html >> >>> >> >>> Signed-off-by: Heng Qi >> >>> Reviewed-by: Xuan Zhuo >> >>> --- >> >>> This patch is on top of Alvaro's latest v7 patch: https://lists.oasi= s-open.org/archives/virtio-dev/202302/msg00431.html . >> >>> >> >>> v6->v7: >> >>> 1. Clarify the relationship of VIRTIO_NET_CTRL_NOTF_COAL_TX/= RX_SET and VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET. @Alvaro Karsz, @Michael S. Tsi= rkin >> >>> 2. Remove formula for vqn range. @Parav Pandit >> >>> 3. Some expressions are clearer. @Parav Pandit, @Michael S. = Tsirkin >> >>> >> >>> v5->v6: >> >>> 1. Explain that the device may set a different value than th= e one passed in by the driver. @David Edmondson >> >> A couple of things about this: >> >> - why say "a value close to a power of 2" - couldn't the device pick = any >> >> value it chooses? >> > >> > This is just a hint from the spec, it is "MAY", not "MUST" in the >> > conformance of the device, the device can still set any value it >> > receives. >>=20 >> Okay. >>=20 >> > And, since "virtqueue notification coalescing" feature will be used in >> > the netdim [1] algorithm, >> > and the coalescing moderation of netdim is roughly as follows, so it >> > is allowed to give the hint in the spec: >> > " >> > #define NET_DIM_RX_EQE_PROFILES { \ >> > {.usec =3D 1, .pkts =3D NET_DIM_DEFAULT_RX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 8, .pkts =3D NET_DIM_DEFAULT_RX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 64, .pkts =3D NET_DIM_DEFAULT_RX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 128, .pkts =3D NET_DIM_DEFAULT_RX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 256, .pkts =3D NET_DIM_DEFAULT_RX_CQ_PKTS_FROM_EQE,} \ >> > } >> > >> > #define NET_DIM_RX_CQE_PROFILES { \ >> > {.usec =3D 2, .pkts =3D 256,}, \ >> > {.usec =3D 8, .pkts =3D 128,}, \ >> > {.usec =3D 16, .pkts =3D 64,}, \ >> > {.usec =3D 32, .pkts =3D 64,}, \ >> > {.usec =3D 64, .pkts =3D 64,} \ >> > } >> > >> > #define NET_DIM_TX_EQE_PROFILES { \ >> > {.usec =3D 1, .pkts =3D NET_DIM_DEFAULT_TX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 8, .pkts =3D NET_DIM_DEFAULT_TX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 32, .pkts =3D NET_DIM_DEFAULT_TX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 64, .pkts =3D NET_DIM_DEFAULT_TX_CQ_PKTS_FROM_EQE,}, \ >> > {.usec =3D 128, .pkts =3D NET_DIM_DEFAULT_TX_CQ_PKTS_FROM_EQE,} \ >> > } >> > >> > #define NET_DIM_TX_CQE_PROFILES { \ >> > {.usec =3D 5, .pkts =3D 128,}, \ >> > {.usec =3D 8, .pkts =3D 64,}, \ >> > {.usec =3D 16, .pkts =3D 32,}, \ >> > {.usec =3D 32, .pkts =3D 32,}, \ >> > {.usec =3D 64, .pkts =3D 32,} \ >> > } >> > " >> > [1]=C2=A0 https://docs.kernel.org/networking/net_dim.html >> > >> >> - I think that we need to be more explicit that the values passed in = the >> >> SET request may not be honoured exactly. >> > >> > Yes, there are already examples in the current spec: >> > " >> > +When a device receives a command of the VIRTIO_NET_CTRL_NOTF_COAL >> > class to set a coalescing parameter, >> > +it may set the parameter to a value close to a power of 2. For exampl= e: >> > +If the device receives \field{max_usecs} =3D 7 from the >> > VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command, it may set \field{max_usecs} >> > =3D 8 for a given enabled virtqueue. >> > " >> > If you find this unclear, do you need more examples or clarification, >> > or do you have a better way? >>=20 >> Explicit is good: >>=20 >> When a device receives a command of the VIRTIO_NET_CTRL_NOTF_COAL class >> to set a coalescing parameter it may choose to use a value different to >> that specified in the command, for example a power of two value close to >> the specified parameter. > > > Hmm. This clarification actually belongs in Alvaro's patch btw, no? > Basically with the best-effort sentence. Sure. >> The value chosen by the device can be retrieved >> using the VIRTIO_NET_CTRL_NOTF_VQ_GET command. > > I do however feel that maybe we should not allow any value. > Values lower than what is specified are definitely ok. Amusingly, or not, that runs counter to the provided example (setting 7 usecs, getting 8). > >> >> - should the chosen value be returned in the SET call? (Not too fusse= d >> >> about this, though it may result in an implementation immediately >> >> calling GET after SET to see what actually happened.) >> > >> > As you said, I think we can just call GET to view. >> > >> >> - the example which shows how the global and per-VQ set operations >> >> interact is reasonably worded ("the device responds with coalescin= g >> >> parameters of virtqueue1 set by command5"), so that seems okay. >> > >> > Yeah. >> > >> > Thanks. >> > >> >>> v4->v5: >> >>> 1. Add the correspondence between virtio_net_ctrl_coal and v= irtio_net_ctrl_coal_vq and control commands. @Michael S. Tsirkin >> >>> 2. Add read and write attributes for each field. @Michael S.= Tsirkin >> >>> 3. A clearer description of how to set coalescing parameters= for vq reset. @Michael S. Tsirkin >> >>> 4. Fix some syntax errors. @Michael S. Tsirkin, @David Edmon= dson >> >>> >> >>> v3->v4: >> >>> 1. Include virtio_net_ctrl_coal in the virtio_net_ctrl_coal_= vq structure. @Alvaro Karsz >> >>> 2. Add consideration of vq reset. @Michael S. Tsirkin, @Para= v Pandit, @Alvaro Karsz >> >>> 3. Avoid too many examples by giving a comprehensive example= . @Michael S. Tsirkin >> >>> 4. Fix typos and streamline clarifications. @Michael S. Tsir= kin, @Parav Pandit, @Alvaro Karsz >> >>> >> >>> v2->v3: >> >>> 1. Add the netdim link. @Parav Pandit >> >>> 2. VIRTIO_NET_F_VQ_NOTF_COAL no longer depends on VIRTIO_NET= _F_NOTF_COAL. @Michael S. Tsirkin, @Alvaro Karsz >> >>> 3. _VQ_GET is explained more. @Michael S. Tsirkin >> >>> 4. Add more examples to avoid misunderstandings. @Michael S.= Tsirkin >> >>> 5. Clarify some statements. @Michael S. Tsirkin, @Parav Pand= it, @Alvaro Karsz >> >>> 6. Adjust the virtio_net_ctrl_coal_vq structure. @Michael S.= Tsirkin >> >>> 7. Fix some typos. @Michael S. Tsirkin >> >>> >> >>> v1->v2: >> >>> 1. Rename VIRTIO_NET_F_PERQUEUE_NOTF_COAL to VIRTIO_NET_F_VQ= _NOTF_COAL. @Michael S. Tsirkin >> >>> 2. Use the \field{vqn} instead of the qid. @Michael S. Tsirk= in >> >>> 3. Unify tx and rx control structres into one structure virt= io_net_ctrl_coal_vq. @Michael S. Tsirkin >> >>> 4. Add a new control command VIRTIO_NET_CTRL_NOTF_COAL_VQ. @= Michael S. Tsirkin, @Parav Pandit, @Alvaro Karsz >> >>> 5. The special value 0xFFF is removed because VIRTIO_NET_CTR= L_NOTF_COAL can be used. @Alvaro Karsz >> >>> 6. Clarify some special scenarios. @Michael S. Tsirkin, @Par= av Pandit, @Alvaro Karsz >> >>> >> >>> device-types/net/description.tex | 99 ++++++++++++++++++++++++++++= ++-- >> >>> 1 file changed, 94 insertions(+), 5 deletions(-) >> >>> >> >>> diff --git a/device-types/net/description.tex b/device-types/net/des= cription.tex >> >>> index e71e33b..745e4d9 100644 >> >>> --- a/device-types/net/description.tex >> >>> +++ b/device-types/net/description.tex >> >>> @@ -83,6 +83,8 @@ \subsection{Feature bits}\label{sec:Device Types /= Network Device / Feature bits >> >>> \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through cont= rol >> >>> channel. >> >>> +\item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports virtqueue >> >>> notification coalescing. >> >>> + >> >>> \item[VIRTIO_NET_F_NOTF_COAL(53)] Device supports notifications co= alescing. >> >>> \item[VIRTIO_NET_F_GUEST_USO4 (54)] Driver can receive USOv4 >> >>> packets. >> >>> @@ -139,6 +141,7 @@ \subsubsection{Feature bit requirements}\label{s= ec:Device Types / Network Device >> >>> \item[VIRTIO_NET_F_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ. >> >>> \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or VIR= TIO_NET_F_HOST_TSO6. >> >>> \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ. >> >>> +\item[VIRTIO_NET_F_VQ_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ. >> >>> \end{description} >> >>> \subsubsection{Legacy Interface: Feature bits}\label{sec:Device >> >>> Types / Network Device / Feature bits / Legacy Interface: Feature >> >>> bits} >> >>> @@ -1508,6 +1511,14 @@ \subsubsection{Control Virtqueue}\label{sec:D= evice Types / Network Device / Devi >> >>> If the VIRTIO_NET_F_NOTF_COAL feature is negotiated, the driver ca= n >> >>> send control commands for dynamically changing the coalescing para= meters. >> >>> +If the VIRTIO_NET_F_VQ_NOTF_COAL feature is negotiated: >> >>> +\begin{itemize} >> >>> +\item a driver can send a VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command = to set coalescing parameters of a given >> >>> + enabled transmit/receive virtqueue. >> >>> +\item a driver can send a VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET command = to a device, and the device responds with >> >>> + coalescing parameters of a given enabled transmit/receive vir= tqueue. >> >>> +\end{itemize} >> >>> + >> >>> \begin{note} >> >>> The behavior of the device in response to these commands is best-e= ffort: >> >>> the device may generate notifications more or less frequently than= specified. >> >>> @@ -1519,25 +1530,76 @@ \subsubsection{Control Virtqueue}\label{sec:= Device Types / Network Device / Devi >> >>> le32 max_usecs; >> >>> }; >> >>> +struct virtio_net_ctrl_coal_vq { >> >>> + le16 vqn; >> >>> + le16 reserved; >> >>> + struct virtio_net_ctrl_coal coal; >> >>> +}; >> >>> + >> >>> #define VIRTIO_NET_CTRL_NOTF_COAL 6 >> >>> #define VIRTIO_NET_CTRL_NOTF_COAL_TX_SET 0 >> >>> #define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET 1 >> >>> + #define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET 2 >> >>> + #define VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET 3 >> >>> \end{lstlisting} >> >>> +The VIRTIO_NET_CTRL_NOTF_COAL_TX_SET and >> >>> VIRTIO_NET_CTRL_NOTF_COAL_RX_SET commands use the >> >>> +virtio_net_ctrl_coal structure to set \field{max_usecs} and \field{= max_packets} for all >> >>> +transmit/receive virtqueues. >> >>> + >> >>> +The VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command uses the virtio_net_ct= rl_coal_vq structure >> >>> +to set \field{max_usecs} and \field{max_packets} for the supplied v= irtqueue number \field{vqn}. >> >>> + >> >>> +The VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET command gets the values of \fi= eld{max_usecs} and >> >>> +\field{max_packets} of the specified virtqueue from the device by s= etting \field{vqn} >> >>> +in the virtio_net_ctrl_coal_vq structure. >> >>> + >> >>> +# Read/Write attributes for coalescing parameters >> >>> +\begin{itemize} >> >>> +\item For commands VIRTIO_NET_CTRL_NOTF_COAL_TX_SET and VIRTIO_NET_= CTRL_NOTF_COAL_RX_SET, \field{max_usecs} >> >>> + and \field{max_packets} are write-only for a driver. >> >>> +\item For the command VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET, \field{vqn}= , \field{reserved}, \field{max_usecs} >> >>> + and \field{max_packets} are write-only for a driver. >> >>> +\item For the command VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET, \field{vqn}= and \field{reserved} are write-only >> >>> + for a driver, and, \field{max_usecs} and \field{max_packets} = are read-only for the driver. >> >>> +\end{itemize} >> >>> + >> >>> Coalescing parameters: >> >>> \begin{itemize} >> >>> +\item \field{vqn}: The virtqueue number of an enabled transmit or r= eceive virtqueue. >> >>> \item \field{max_usecs} for RX: Maximum number of microseconds to = delay a RX notification. >> >>> \item \field{max_usecs} for TX: Maximum number of microseconds to = delay a TX notification. >> >>> \item \field{max_packets} for RX: Maximum number of packets to rec= eive before a RX notification. >> >>> \item \field{max_packets} for TX: Maximum number of packets to sen= d before a TX notification. >> >>> \end{itemize} >> >>> -The class VIRTIO_NET_CTRL_NOTF_COAL has 2 commands: >> >>> +\field{reserved} is reserved and it is ignored by a device. >> >>> + >> >>> +The class VIRTIO_NET_CTRL_NOTF_COAL has 4 commands: >> >>> \begin{enumerate} >> >>> -\item VIRTIO_NET_CTRL_NOTF_COAL_TX_SET: set the \field{max_usecs} a= nd \field{max_packets} parameters for all transmit virtqueues. >> >>> -\item VIRTIO_NET_CTRL_NOTF_COAL_RX_SET: set the \field{max_usecs} a= nd \field{max_packets} parameters for all receive virtqueues. >> >>> +\item VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET: set the \field{max_usecs} a= nd \field{max_packets} parameters for an enabled transmit/receive >> >>> + virtqueue whose number is \= field{vqn}. >> >>> +\item VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET: the device returns the \fie= ld{max_usecs} and \field{max_packets} parameters for an enabled >> >>> + transmit/receive virtqueue = whose number is \field{vqn}. >> >>> +\item VIRTIO_NET_CTRL_NOTF_COAL_TX_SET: have the same effect of set= ting coalescing parameters as the VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command = repeated for >> >>> + each virtqueue of transmitq= 1\ldots transmitqN. >> >>> +\item VIRTIO_NET_CTRL_NOTF_COAL_RX_SET: have the same effect of set= ting coalescing parameters as the VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command = repeated for >> >>> + each virtqueue of receiveq1= \ldots receiveqN. >> >>> \end{enumerate} >> >>> +If coalescing parameters are being set, the device applies the >> >>> last coalescing parameters received for a >> >>> +virtqueue, regardless of the command used to set the parameters. Fo= r example with 2 pairs of virtqueues: >> >>> +# Command sequence >> >>> +Each of the following commands sets \field{max_usecs} and \field{ma= x_packets} parameters for virtqueues. >> >>> +\begin{itemize} >> >>> +\item Command1: VIRTIO_NET_CTRL_NOTF_COAL_RX_SET sets coalescing >> > parameters for virtqueue0 and virtqueue2, and, virtqueue1 and >> > virtqueue3 retain their previous parameter values. >> >>> +\item Command2: VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET with \field{vqn} = =3D 0 sets coalescing parameters for virtqueue0, and virtqueue2 retains the= values from command1. >> >>> +\item Command3: VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET with \field{vqn} = =3D 0, the device responds with coalescing parameters of virtqueue0 set by = command2. >> >>> +\item Command4: VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET with \field{vqn} = =3D 1 sets coalescing parameters for virtqueue1, and virtqueue3 retains its= previous values. >> >>> +\item Command5: VIRTIO_NET_CTRL_NOTF_COAL_TX_SET sets coalescing pa= rameters for virtqueue1 and virtqueue3, and overrides the values set by com= mand4. >> >>> +\item Command6: VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET with \field{vqn} = =3D 1, the device responds with coalescing parameters of virtqueue1 set by = command5. >> >>> +\end{itemize} >> >>> + >> >>> \subparagraph{Operation}\label{sec:Device Types / Network Device /= Device Operation / Control Virtqueue / Notifications Coalescing / Operatio= n} >> >>> The device sends a used buffer notification once the >> >>> notification conditions are met and if the notifications are not >> >>> suppressed as explained in \ref{sec:Basic Facilities of a Virtio >> >>> Device / Virtqueues / Used Buffer Notification Suppression}. >> >>> @@ -1549,6 +1611,15 @@ \subsubsection{Control Virtqueue}\label{sec:D= evice Types / Network Device / Devi >> >>> When the device has \field{max_usecs} =3D 0 or >> >>> \field{max_packets} =3D 0, the notification conditions are met after >> >>> every packet received/sent. >> >>> +When a device receives a command of the >> >>> VIRTIO_NET_CTRL_NOTF_COAL class to set a coalescing parameter, >> >>> +it may set the parameter to a value close to a power of 2. For exam= ple: >> >>> +If the device receives \field{max_usecs} =3D 7 from the VIRTIO_NET_= CTRL_NOTF_COAL_VQ_SET command, it may set \field{max_usecs} =3D 8 for a giv= en enabled virtqueue. >> >>> + >> >>> +When the device receives the VIRTIO_NET_CTRL_NOTF_COAL_TX_SET and V= IRTIO_NET_CTRL_NOTF_COAL_RX_SET commands, >> >>> +it saves the values of coalescing parameters as global values, and = the VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command >> >>> +does not change the global values. If the device is reset, the glob= al values will be set to 0. >> >>> +When a virtqueue is enabled after virtqueue reset, its coalescing p= arameters are set to global values. >> >>> + >> >>> \subparagraph{RX Example}\label{sec:Device Types / Network Device = / Device Operation / Control Virtqueue / Notifications Coalescing / RX Exam= ple} >> >>> If, for example: >> >>> @@ -1585,11 +1656,29 @@ \subsubsection{Control Virtqueue}\label{sec:= Device Types / Network Device / Devi >> >>> \drivernormative{\subparagraph}{Notifications >> >>> Coalescing}{Device Types / Network Device / Device Operation / >> >>> Control Virtqueue / Notifications Coalescing} >> >>> -If the VIRTIO_NET_F_NOTF_COAL feature has not been negotiated, >> >>> the driver MUST NOT issue VIRTIO_NET_CTRL_NOTF_COAL commands. >> >>> +If neither the VIRTIO_NET_F_NOTF_COAL nor the VIRTIO_NET_F_VQ_NOTF_= COAL feature >> >>> +has been negotiated, the driver MUST NOT issue VIRTIO_NET_CTRL_NOTF= _COAL commands. >> >>> + >> >>> +A driver MUST ignore the values of coalescing parameters received f= rom the VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET command if a device responds with = VIRTIO_NET_ERR. >> >>> \devicenormative{\subparagraph}{Notifications >> >>> Coalescing}{Device Types / Network Device / Device Operation / >> >>> Control Virtqueue / Notifications Coalescing} >> >>> -A device SHOULD respond to the VIRTIO_NET_CTRL_NOTF_COAL >> >>> commands with VIRTIO_NET_ERR if it was not able to change the >> >>> parameters. >> >>> +A device SHOULD respond to VIRTIO_NET_CTRL_NOTF_COAL_TX_SET and > VIRTIO_NET_CTRL_NOTF_COAL_RX_SET commands with VIRTIO_NET_ERR if it > was not able to change the parameters. >> >>> + >> >>> +A device MUST respond to the VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET comma= nd with VIRTIO_NET_ERR if it was not able to change the parameters. >> >>> + >> >>> +A device MUST respond to VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET and VIRTI= O_NET_CTRL_NOTF_COAL_VQ_GET commands with VIRTIO_NET_ERR if the given virtq= ueue is disabled. >> >>> + >> >>> +The VIRTIO_NET_CTRL_NOTF_COAL_TX_SET and VIRTIO_NET_CTRL_NOTF_COAL_= RX_SET commands set coalescing parameters for all transmit/receive >> >>> +virtqueues respectively and values of coalescing parameters are rec= orded as global values by a device. >> >>> +The device MUST set the global values of coalescing parameters to 0= after being reset. >> >>> +The VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET command sets the coalescing pa= rameters for a given enabled virtqueue without changing the global values. >> >>> + >> >>> +After disabling and re-enabling a virtqueue, the device MUST revert= coalescing parameters of the virtqueue to the global values. >> >>> + >> >>> +A device MAY set the coalescing parameter to a value close to a pow= er of 2 value. >> >>> + >> >>> +A device MUST ignore \field{reserved}. >> >>> A device SHOULD NOT send used buffer notifications to the >> >>> driver if the notifications are suppressed, even if the >> >>> notification conditions are met. >> > >> > >> > 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/mailin= g-lists >> > Committee: https://www.oasis-open.org/committees/virtio/ >> > Join OASIS: https://www.oasis-open.org/join/ >> --=20 >> Come down, come talk to me. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org --=20 Modern people tend to dance. 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