[virtio-dev] [PATCH v3 0/2] Introducing RSS to virtio-net

[virtio-dev] [PATCH v3 0/2] Introducing RSS to virtio-net

[Sameeh Jubran]

From: Sameeh Jubran <sjubran@redhat.com>

Please ignore the feature number value (60) in the patch, it is not final for now.

Difference from v2:

* Dropped RSS_HASH_FUNCTION_NONE flag from RSS as it seems to be
  useless.
* Added more comments to the code.
* Beautifications.
* Fixed some sentences to make them clearer.


Sameeh Jubran (2):
  content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature
  content: net: steering mode: Add RSS

 content.tex | 170 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 170 insertions(+)

-- 
2.13.6


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[virtio-dev] [PATCH v3 1/2] content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature

[Sameeh Jubran]

From: Sameeh Jubran <sameeh.j@gmail.com>

This commit introduces steering mode into network device. Steering
mode is a general infrastructure for various steering modes that can
be implemented on top of it such as Automatic and RSS.

Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
---
 content.tex | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/content.tex b/content.tex
index c840588..6b1f7ca 100644
--- a/content.tex
+++ b/content.tex
@@ -3115,6 +3115,9 @@ features.
 
 \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
     channel.
+
+\item[VIRTIO_NET_F_CTRL_STEERING_MODE(60)] Device supports configurable steering
+    mode.
 \end{description}
 
 \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device / Feature bits / Feature bit requirements}
@@ -3317,6 +3320,8 @@ struct virtio_net_hdr {
         le16 csum_start;
         le16 csum_offset;
         le16 num_buffers;
+// Only if VIRTIO_NET_F_CTRL_STEERING_MODE has been negotiated
+        le64 hash;
 };
 \end{lstlisting}
 
@@ -4013,6 +4018,62 @@ MUST format \field{virtqueue_pairs}
 according to the native endian of the guest rather than
 (necessarily when not using the legacy interface) little-endian.
 
+\paragraph{Steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode}
+
+\begin{lstlisting}
+// steering mode flags
+#define STEERING_MODE_AUTO          0x1
+
+// Used by the devide for returning to the driver the supported steering modes
+struct virtio_net_steering_modes {
+le32 steering_modes;
+};
+
+struct virtio_net_steering_mode {
+le32 steering_mode;
+le32 command;
+
+// A union which can be used for passing structures to one of the sub modes
+    union {
+    }
+};
+
+#define VIRTIO_NET_F_CTRL_STEERING_MODE     27
+
+#define VIRTIO_NET_CTRL_STEERING_MODE                7
+#define VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES        0
+#define VIRTIO_NET_CTRL_SM_CONTROL                    1
+\end{lstlisting}
+
+If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can send control commands for the
+configuring the steering mode. There are multiple steering modes and they can be configured using
+the VIRTIO_NET_CTRL_SM_CONTROL command. Each mode has it's own set of commands.
+
+The auto steering mode is the default mode if nothing else has been configured by the driver
+and the VIRTIO_NET_F_CTRL_STEERING_MODE feature is acked by the driver.
+
+The class VIRTIO_NET_CTRL_STEERING_MODE has two commands:
+
+\begin{enumerate}
+
+\item VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES is used for getting the supported steering modes by the device.
+	The command should be executed by the driver before attempting to configure the steering mode. Once the device
+	receives this command it should fill the virtio_net_steering_modes structure with the supported steering mode
+	flags.
+
+\item The command VIRTIO_NET_CTRL_SM_CONTROL is used for controlling the different steering modes. Each steering mode
+	has its own set of commands. When executing this command the structure virtio_net_steering_mode should be used as follows:
+	the \field{steering_mode} should be filled with one of the steering mode flags along with an appropriate command from the chosen
+	steering mode. The union of virtio_net_steering_mode should be used and filled as the mode's command suggests.
+\end{enumerate}
+
+If this feature has been negotiated, the virtio header has an additional
+\field{hash} field attached to it.
+
+\subparagraph{Automatic Receive Steering}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Automatic Receive Steering}
+
+This is the default steering mode, please refer to the "Automatic receive steering in multiqueue" section.
+
 \paragraph{Offloads State Configuration}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration}
 
 If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can
-- 
2.13.6


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[virtio-dev] [PATCH v3 2/2] content: net: steering mode: Add RSS

[Sameeh Jubran]

From: Sameeh Jubran <sjubran@redhat.com>

This commit introduces the RSS feature into virtio-net. It is introduced
as a sub mode for a general command which configures the steering mode.

Most modern high end network devices today support configurable hash functions,
this commit introduces RSS - Receive Side Scaling - [1] to virtio net device.

The RSS is a technology from Microsoft that boosts network device performance
by efficiently distributing the traffic among the CPUs in a multiprocessor
system.

This feature is supported in most of the modern network cards as well as most
modern OSes including Linux and Windows. It is worth mentioning that both DPDK
and Hyper-v support RSS too.

[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/network/ndis-receive-side-scaling2

Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
---
 content.tex | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)

diff --git a/content.tex b/content.tex
index 6b1f7ca..3ea2b6a 100644
--- a/content.tex
+++ b/content.tex
@@ -4023,6 +4023,7 @@ according to the native endian of the guest rather than
 \begin{lstlisting}
 // steering mode flags
 #define STEERING_MODE_AUTO          0x1
+#define STEERING_MODE_RSS           0x2
 
 // Used by the devide for returning to the driver the supported steering modes
 struct virtio_net_steering_modes {
@@ -4035,6 +4036,7 @@ le32 command;
 
 // A union which can be used for passing structures to one of the sub modes
     union {
+    struct virtio_net_rss rss_conf;
     }
 };
 
@@ -4074,6 +4076,113 @@ If this feature has been negotiated, the virtio header has an additional
 
 This is the default steering mode, please refer to the "Automatic receive steering in multiqueue" section.
 
+\subparagraph{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
+
+\begin{lstlisting}
+#define RSS_HASH_FUNCTION_TOEPLITZ  0x1
+#define RSS_HASH_FUNCTION_SYMMETRIC 0x2
+
+// Hash function fields
+#define RSS_HASH_FIELDS_IPV4          0x00000100
+#define RSS_HASH_FIELDS_TCP_IPV4      0x00000200
+#define RSS_HASH_FIELDS_IPV6          0x00000400
+#define RSS_HASH_FIELDS_IPV6_EX       0x00000800
+#define RSS_HASH_FIELDS_TCP_IPV6      0x00001000
+#define RSS_HASH_FIELDS_TCP_IPV6_EX   0x00002000
+
+struct virtio_net_rss_supported_hash{
+le32 hash_function;
+}
+
+struct virtio_net_rss {
+le32 hash_function;
+le32 hash_function_flags;
+le32 hash_key_length;
+le32 indirection_table_length;
+	struct {
+		le32 hash_key[hash_key_length];
+		le32 indirection_table[indirection_table_length];
+	}
+};
+
+#define VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS   0
+#define VIRTIO_NET_SM_CTRL_RSS_SET                       1
+\end{lstlisting}
+
+If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can send control
+commands using the VIRTIO_NET_CTRL_SM_CONTROL command along with the STEERING_MODE_RSS
+flag for configuring RSS the virtio_net_steering_mode should be filled. The
+\field{steering_mode} field should be filled with the STEERING_MODE_RSS flag along
+with one of the VIRTIO_NET_SM_CTRL_RSS commands in the \field{command} field. The
+\field{rss_conf} field should be used.
+
+The class VIRTIO_NET_CTRL_RSS has two commands:
+
+\begin{enumerate}
+\item VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS returns the hash functions
+	supported by the device to the driver.
+\item VIRTIO_NET_SM_CTRL_RSS_SET applies the new RSS configuration. The command is
+	used by the driver for setting RSS hash function, hash key and
+	indirection table in the device.
+\end{enumerate}
+
+\devicenormative{\subparagraph}{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
+
+The device MUST fill the virtio_net_rss_supported_hash structure with the hash
+functions it supports and return the structure to the driver. One or more
+flags of the RSS_HASH_FUNCTION flags MUST be used to fill the \field{hash_function}
+field.
+
+The device MUST drop all previous RSS configuration upon receiving
+VIRTIO_NET_SM_CTRL_RSS_SET command.
+
+The device MUST set the RSS configuration according to the settings provided as
+follows, once the configuration process is completed the device SHOULD apply
+the hash function to each of the incoming packets with regards to the flags in
+the \field{hash_function_flags} fields and distribute the packets through the
+virqueues using the calculated hash and the indirection table that were earlier
+provided by the driver.
+
+Setting RSS configuration
+\begin{enumerate}
+\item The driver fills all of the fields and passes them through the control
+	queue to the device.
+
+\item The device sets the RSS configuration as provided by the driver.
+
+\item If the device successfully applied the configuration, on each packet
+	received the device MUST calculate the hash for the packet using
+	the fields specified in \field{hash_function_flags} and store it in the
+	virtio-net header in the \field{hash} field and the hash fields
+	used in the calculation.
+\end{enumerate}
+
+\drivernormative{\subparagraph}{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
+
+If the driver wants to set RSS hash it should fill the RSS structure fields
+as follows:
+
+\begin{itemize}
+\item The driver SHOULD choose the hash function that SHOULD be used and fill
+	it in the \field{hash_function} field along with the appropriate flags
+	in the \field{hash_function_flags} field. These flags indicate to the
+	device which packet fields MUST be used in the calculation process of
+	the hash.
+\item Once the hash function has been chosen a hash key should also be set by
+	the driver in the \field{hash_key} field, the length of the key should
+	be stored in the \field{hash_key_length} field.
+\item Lastly the driver should fill the indirection table array in the
+	\field{indirection_table} field while setting the array length in
+	\field{indirection_table_length}. This structure is used by the device
+	for determining in which RX virt queue the packet should be placed.
+\end{itemize}
+Once the configuration phase is over successfully, the packets SHOULD have the
+\field{hash} field with the hash value that was calculated by the device.
+
+Whenever the driver wants to stop performing RSS, it can switch back to
+Automatic Steering Mode using the VIRTIO_NET_CTRL_SM_CONTROL command along with
+the STEERING_MODE_AUTO flag.
+
 \paragraph{Offloads State Configuration}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration}
 
 If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can
-- 
2.13.6


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[virtio-dev] Re: [PATCH v3 0/2] Introducing RSS to virtio-net

[Sameeh Jubran]

[-- Attachment #1: Type: text/plain, Size: 852 bytes --]

ping

On Wed, Apr 18, 2018 at 1:46 PM, Sameeh Jubran <sameeh@daynix.com> wrote:

> From: Sameeh Jubran <sjubran@redhat.com>
>
> Please ignore the feature number value (60) in the patch, it is not final
> for now.
>
> Difference from v2:
>
> * Dropped RSS_HASH_FUNCTION_NONE flag from RSS as it seems to be
>   useless.
> * Added more comments to the code.
> * Beautifications.
> * Fixed some sentences to make them clearer.
>
>
> Sameeh Jubran (2):
>   content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature
>   content: net: steering mode: Add RSS
>
>  content.tex | 170 ++++++++++++++++++++++++++++++
> ++++++++++++++++++++++++++++++
>  1 file changed, 170 insertions(+)
>
> --
> 2.13.6
>
>


-- 
Respectfully,
*Sameeh Jubran*
*Linkedin <https://il.linkedin.com/pub/sameeh-jubran/87/747/a8a>*
*Software Engineer @ Daynix <http://www.daynix.com>.*

[-- Attachment #2: Type: text/html, Size: 2515 bytes --]

Re: [virtio-dev] [PATCH v3 1/2] content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature

[Vijayabhaskar Balakrishna]

Hi Sameeh,

See inline..
On 4/18/2018 3:46 AM, Sameeh Jubran wrote:
> From: Sameeh Jubran <sameeh.j@gmail.com>
>
> This commit introduces steering mode into network device. Steering
> mode is a general infrastructure for various steering modes that can
> be implemented on top of it such as Automatic and RSS.
>
> Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
> ---
>   content.tex | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 61 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index c840588..6b1f7ca 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -3115,6 +3115,9 @@ features.
>   
>   \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
>       channel.
> +
> +\item[VIRTIO_NET_F_CTRL_STEERING_MODE(60)] Device supports configurable steering
> +    mode.
>   \end{description}
>   
>   \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device / Feature bits / Feature bit requirements}
> @@ -3317,6 +3320,8 @@ struct virtio_net_hdr {
>           le16 csum_start;
>           le16 csum_offset;
>           le16 num_buffers;
> +// Only if VIRTIO_NET_F_CTRL_STEERING_MODE has been negotiated
> +        le64 hash;
>   };
>   \end{lstlisting}
>   
> @@ -4013,6 +4018,62 @@ MUST format \field{virtqueue_pairs}
>   according to the native endian of the guest rather than
>   (necessarily when not using the legacy interface) little-endian.
>   
> +\paragraph{Steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode}
> +
> +\begin{lstlisting}
> +// steering mode flags
> +#define STEERING_MODE_AUTO          0x1
> +
> +// Used by the devide for returning to the driver the supported steering modes
> +struct virtio_net_steering_modes {
> +le32 steering_modes;
> +};
> +
> +struct virtio_net_steering_mode {
> +le32 steering_mode;
> +le32 command;
> +
> +// A union which can be used for passing structures to one of the sub modes
> +    union {
> +    }
> +};
> +
> +#define VIRTIO_NET_F_CTRL_STEERING_MODE     27
> +
> +#define VIRTIO_NET_CTRL_STEERING_MODE                7
> +#define VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES        0
> +#define VIRTIO_NET_CTRL_SM_CONTROL                    1
> +\end{lstlisting}
> +
> +If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can send control commands for the
> +configuring the steering mode. There are multiple steering modes and they can be configured using
> +the VIRTIO_NET_CTRL_SM_CONTROL command. Each mode has it's own set of commands.
> +
> +The auto steering mode is the default mode if nothing else has been configured by the driver
> +and the VIRTIO_NET_F_CTRL_STEERING_MODE feature is acked by the driver.
> +
> +The class VIRTIO_NET_CTRL_STEERING_MODE has two commands:
> +
> +\begin{enumerate}
> +
> +\item VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES is used for getting the supported steering modes by the device.
> +	The command should be executed by the driver before attempting to configure the steering mode. Once the device
> +	receives this command it should fill the virtio_net_steering_modes structure with the supported steering mode
> +	flags.
> +
> +\item The command VIRTIO_NET_CTRL_SM_CONTROL is used for controlling the different steering modes. Each steering mode
> +	has its own set of commands. When executing this command the structure virtio_net_steering_mode should be used as follows:
> +	the \field{steering_mode} should be filled with one of the steering mode flags along with an appropriate command from the chosen
should we say? should be filled with one of the supported steering mode
> +	steering mode. The union of virtio_net_steering_mode should be used and filled as the mode's command suggests.
> +\end{enumerate}
> +
> +If this feature has been negotiated, the virtio header has an additional
should say:
virtio net header has an additional
> +\field{hash} field attached to it.
> +
> +\subparagraph{Automatic Receive Steering}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Automatic Receive Steering}
> +
> +This is the default steering mode, please refer to the "Automatic receive steering in multiqueue" section.
I see referred section named in the spec as "Automatic receive steering 
in multiqueue mode".
> +
>   \paragraph{Offloads State Configuration}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration}
>   
>   If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can


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Re: [virtio-dev] [PATCH v3 2/2] content: net: steering mode: Add RSS

[Vijayabhaskar Balakrishna]

Hi Sameeh,

See inline..

Thanks,
Vijay
On 4/18/2018 3:46 AM, Sameeh Jubran wrote:
> From: Sameeh Jubran <sjubran@redhat.com>
>
> This commit introduces the RSS feature into virtio-net. It is introduced
> as a sub mode for a general command which configures the steering mode.
>
> Most modern high end network devices today support configurable hash functions,
> this commit introduces RSS - Receive Side Scaling - [1] to virtio net device.
>
> The RSS is a technology from Microsoft that boosts network device performance
> by efficiently distributing the traffic among the CPUs in a multiprocessor
> system.
>
> This feature is supported in most of the modern network cards as well as most
> modern OSes including Linux and Windows. It is worth mentioning that both DPDK
> and Hyper-v support RSS too.
>
> [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/network/ndis-receive-side-scaling2
>
> Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
> ---
>   content.tex | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 109 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index 6b1f7ca..3ea2b6a 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -4023,6 +4023,7 @@ according to the native endian of the guest rather than
>   \begin{lstlisting}
>   // steering mode flags
>   #define STEERING_MODE_AUTO          0x1
> +#define STEERING_MODE_RSS           0x2
>   
>   // Used by the devide for returning to the driver the supported steering modes
>   struct virtio_net_steering_modes {
> @@ -4035,6 +4036,7 @@ le32 command;
>   
>   // A union which can be used for passing structures to one of the sub modes
>       union {
> +    struct virtio_net_rss rss_conf;
>       }
>   };
>   
> @@ -4074,6 +4076,113 @@ If this feature has been negotiated, the virtio header has an additional
>   
>   This is the default steering mode, please refer to the "Automatic receive steering in multiqueue" section.
>   
> +\subparagraph{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
> +
> +\begin{lstlisting}
> +#define RSS_HASH_FUNCTION_TOEPLITZ  0x1
> +#define RSS_HASH_FUNCTION_SYMMETRIC 0x2
> +
> +// Hash function fields
> +#define RSS_HASH_FIELDS_IPV4          0x00000100
> +#define RSS_HASH_FIELDS_TCP_IPV4      0x00000200
> +#define RSS_HASH_FIELDS_IPV6          0x00000400
> +#define RSS_HASH_FIELDS_IPV6_EX       0x00000800
> +#define RSS_HASH_FIELDS_TCP_IPV6      0x00001000
> +#define RSS_HASH_FIELDS_TCP_IPV6_EX   0x00002000
> +
> +struct virtio_net_rss_supported_hash{
> +le32 hash_function;
> +}
> +
> +struct virtio_net_rss {
> +le32 hash_function;
> +le32 hash_function_flags;
> +le32 hash_key_length;
> +le32 indirection_table_length;
> +	struct {
> +		le32 hash_key[hash_key_length];
> +		le32 indirection_table[indirection_table_length];
> +	}
> +};
> +
> +#define VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS   0
> +#define VIRTIO_NET_SM_CTRL_RSS_SET                       1
> +\end{lstlisting}
> +
> +If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can send control
> +commands using the VIRTIO_NET_CTRL_SM_CONTROL command along with the STEERING_MODE_RSS
> +flag for configuring RSS the virtio_net_steering_mode should be filled. The
> +\field{steering_mode} field should be filled with the STEERING_MODE_RSS flag along
> +with one of the VIRTIO_NET_SM_CTRL_RSS commands in the \field{command} field. The
> +\field{rss_conf} field should be used.
May be reworded for clarify along the lines: If 
theVIRTIO_NET_F_CTRL_STEERING_MODE
feature bit is negotiated, the driver can send steering mode control 
command,
VIRTIO_NET_CTRL_SM_CONTROL, with the STEERING_MODE_RSSflag for 
configuring RSS provided
it is one of the supported modes.  The supported steering modes returned 
by device in
response to VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES command issued by the 
driver.
For configuring particulars of RSS steering mode, the various fields of
virtio_net_steering_mode should be filled by the driver.  This includes
\field{steering_mode} with  STEERING_MODE_RSS flag along
with one of the VIRTIO_NET_SM_CTRL_RSS commands in the \field{command}
field in addition to union \field{rss_conf} field members.
> +
> +The class VIRTIO_NET_CTRL_RSS has two commands:
> +
> +\begin{enumerate}
> +\item VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS returns the hash functions
> +	supported by the device to the driver.
> +\item VIRTIO_NET_SM_CTRL_RSS_SET applies the new RSS configuration. The command is
> +	used by the driver for setting RSS hash function, hash key and
> +	indirection table in the device.
> +\end{enumerate}
> +
> +\devicenormative{\subparagraph}{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
> +
> +The device MUST fill the virtio_net_rss_supported_hash structure with the hash
> +functions it supports and return the structure to the driver. One or more
> +flags of the RSS_HASH_FUNCTION flags MUST be used to fill the \field{hash_function}
> +field.
> +
> +The device MUST drop all previous RSS configuration upon receiving
> +VIRTIO_NET_SM_CTRL_RSS_SET command.
> +
> +The device MUST set the RSS configuration according to the settings provided as
> +follows, once the configuration process is completed the device SHOULD apply
> +the hash function to each of the incoming packets with regards to the flags in
> +the \field{hash_function_flags} fields and distribute the packets through the
> +virqueues using the calculated hash and the indirection table that were earlier
> +provided by the driver.
> +
> +Setting RSS configuration
> +\begin{enumerate}
> +\item The driver fills all of the fields and passes them through the control
> +	queue to the device.
> +
> +\item The device sets the RSS configuration as provided by the driver.
> +
> +\item If the device successfully applied the configuration, on each packet
> +	received the device MUST calculate the hash for the packet using
> +	the fields specified in \field{hash_function_flags} and store it in the
> +	virtio-net header in the \field{hash} field and the hash fields
> +	used in the calculation.
> +\end{enumerate}
> +
> +\drivernormative{\subparagraph}{Receive Side Scaling}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
> +
> +If the driver wants to set RSS hash it should fill the RSS structure fields
> +as follows:
> +
> +\begin{itemize}
> +\item The driver SHOULD choose the hash function that SHOULD be used and fill
> +	it in the \field{hash_function} field along with the appropriate flags
> +	in the \field{hash_function_flags} field. These flags indicate to the
> +	device which packet fields MUST be used in the calculation process of
> +	the hash.
> +\item Once the hash function has been chosen a hash key should also be set by
> +	the driver in the \field{hash_key} field, the length of the key should
> +	be stored in the \field{hash_key_length} field.
> +\item Lastly the driver should fill the indirection table array in the
> +	\field{indirection_table} field while setting the array length in
> +	\field{indirection_table_length}. This structure is used by the device
> +	for determining in which RX virt queue the packet should be placed.
> +\end{itemize}
> +Once the configuration phase is over successfully, the packets SHOULD have the
> +\field{hash} field with the hash value that was calculated by the device.
> +
> +Whenever the driver wants to stop performing RSS, it can switch back to
Should we say: ..stop performing RSS or any earlier configured steering 
mode,
> +Automatic Steering Mode using the VIRTIO_NET_CTRL_SM_CONTROL command along with
> +the STEERING_MODE_AUTO flag.
> +
>   \paragraph{Offloads State Configuration}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration}
>   
>   If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can


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Re: [virtio-dev] [PATCH v3 1/2] content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature

[Sameeh Jubran]

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On Fri, Apr 27, 2018 at 9:17 PM, Vijayabhaskar Balakrishna <
vijay.balakrishna@oracle.com> wrote:

> Hi Sameeh,
>
> See inline..
>
> On 4/18/2018 3:46 AM, Sameeh Jubran wrote:
>
>> From: Sameeh Jubran <sameeh.j@gmail.com>
>>
>> This commit introduces steering mode into network device. Steering
>> mode is a general infrastructure for various steering modes that can
>> be implemented on top of it such as Automatic and RSS.
>>
>> Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
>> ---
>>   content.tex | 61 ++++++++++++++++++++++++++++++
>> +++++++++++++++++++++++++++++++
>>   1 file changed, 61 insertions(+)
>>
>> diff --git a/content.tex b/content.tex
>> index c840588..6b1f7ca 100644
>> --- a/content.tex
>> +++ b/content.tex
>> @@ -3115,6 +3115,9 @@ features.
>>     \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
>>       channel.
>> +
>> +\item[VIRTIO_NET_F_CTRL_STEERING_MODE(60)] Device supports configurable
>> steering
>> +    mode.
>>   \end{description}
>>     \subsubsection{Feature bit requirements}\label{sec:Device Types /
>> Network Device / Feature bits / Feature bit requirements}
>> @@ -3317,6 +3320,8 @@ struct virtio_net_hdr {
>>           le16 csum_start;
>>           le16 csum_offset;
>>           le16 num_buffers;
>> +// Only if VIRTIO_NET_F_CTRL_STEERING_MODE has been negotiated
>> +        le64 hash;
>>   };
>>   \end{lstlisting}
>>   @@ -4013,6 +4018,62 @@ MUST format \field{virtqueue_pairs}
>>   according to the native endian of the guest rather than
>>   (necessarily when not using the legacy interface) little-endian.
>>   +\paragraph{Steering mode}\label{sec:Device Types / Network Device /
>> Device Operation / Control Virtqueue / Steering mode}
>> +
>> +\begin{lstlisting}
>> +// steering mode flags
>> +#define STEERING_MODE_AUTO          0x1
>> +
>> +// Used by the devide for returning to the driver the supported steering
>> modes
>> +struct virtio_net_steering_modes {
>> +le32 steering_modes;
>> +};
>> +
>> +struct virtio_net_steering_mode {
>> +le32 steering_mode;
>> +le32 command;
>> +
>> +// A union which can be used for passing structures to one of the sub
>> modes
>> +    union {
>> +    }
>> +};
>> +
>> +#define VIRTIO_NET_F_CTRL_STEERING_MODE     27
>> +
>> +#define VIRTIO_NET_CTRL_STEERING_MODE                7
>> +#define VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES        0
>> +#define VIRTIO_NET_CTRL_SM_CONTROL                    1
>> +\end{lstlisting}
>> +
>> +If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can
>> send control commands for the
>> +configuring the steering mode. There are multiple steering modes and
>> they can be configured using
>> +the VIRTIO_NET_CTRL_SM_CONTROL command. Each mode has it's own set of
>> commands.
>> +
>> +The auto steering mode is the default mode if nothing else has been
>> configured by the driver
>> +and the VIRTIO_NET_F_CTRL_STEERING_MODE feature is acked by the driver.
>> +
>> +The class VIRTIO_NET_CTRL_STEERING_MODE has two commands:
>> +
>> +\begin{enumerate}
>> +
>> +\item VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES is used for getting the
>> supported steering modes by the device.
>> +       The command should be executed by the driver before attempting to
>> configure the steering mode. Once the device
>> +       receives this command it should fill the
>> virtio_net_steering_modes structure with the supported steering mode
>> +       flags.
>> +
>> +\item The command VIRTIO_NET_CTRL_SM_CONTROL is used for controlling the
>> different steering modes. Each steering mode
>> +       has its own set of commands. When executing this command the
>> structure virtio_net_steering_mode should be used as follows:
>> +       the \field{steering_mode} should be filled with one of the
>> steering mode flags along with an appropriate command from the chosen
>>
> should we say? should be filled with one of the supported steering mode

since it is more accurate, we can do that

> +       steering mode. The union of virtio_net_steering_mode should be
>> used and filled as the mode's command suggests.
>> +\end{enumerate}
>> +
>> +If this feature has been negotiated, the virtio header has an additional
>>
> should say:
> virtio net header has an additional

True, I'll change that

>
> +\field{hash} field attached to it.
>> +
>> +\subparagraph{Automatic Receive Steering}{Device Types / Network Device
>> / Device Operation / Control Virtqueue / Steering mode / Automatic Receive
>> Steering}
>> +
>> +This is the default steering mode, please refer to the "Automatic
>> receive steering in multiqueue" section.
>>
> I see referred section named in the spec as "Automatic receive steering in
> multiqueue mode".

I'll add "mode" to this, thanks for catching that

> +
>>   \paragraph{Offloads State Configuration}\label{sec:Device Types /
>> Network Device / Device Operation / Control Virtqueue / Offloads State
>> Configuration}
>>     If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the
>> driver can
>>
>
>


-- 
Respectfully,
*Sameeh Jubran*
*Linkedin <https://il.linkedin.com/pub/sameeh-jubran/87/747/a8a>*
*Software Engineer @ Daynix <http://www.daynix.com>.*

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Re: [virtio-dev] [PATCH v3 2/2] content: net: steering mode: Add RSS

[Sameeh Jubran]

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On Sat, Apr 28, 2018 at 1:09 AM, Vijayabhaskar Balakrishna <
vijay.balakrishna@oracle.com> wrote:

> Hi Sameeh,
>
> See inline..
>
> Thanks,
> Vijay
>
> On 4/18/2018 3:46 AM, Sameeh Jubran wrote:
>
>> From: Sameeh Jubran <sjubran@redhat.com>
>>
>> This commit introduces the RSS feature into virtio-net. It is introduced
>> as a sub mode for a general command which configures the steering mode.
>>
>> Most modern high end network devices today support configurable hash
>> functions,
>> this commit introduces RSS - Receive Side Scaling - [1] to virtio net
>> device.
>>
>> The RSS is a technology from Microsoft that boosts network device
>> performance
>> by efficiently distributing the traffic among the CPUs in a multiprocessor
>> system.
>>
>> This feature is supported in most of the modern network cards as well as
>> most
>> modern OSes including Linux and Windows. It is worth mentioning that both
>> DPDK
>> and Hyper-v support RSS too.
>>
>> [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/ne
>> twork/ndis-receive-side-scaling2
>>
>> Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
>> ---
>>   content.tex | 109 ++++++++++++++++++++++++++++++
>> ++++++++++++++++++++++++++++++
>>   1 file changed, 109 insertions(+)
>>
>> diff --git a/content.tex b/content.tex
>> index 6b1f7ca..3ea2b6a 100644
>> --- a/content.tex
>> +++ b/content.tex
>> @@ -4023,6 +4023,7 @@ according to the native endian of the guest rather
>> than
>>   \begin{lstlisting}
>>   // steering mode flags
>>   #define STEERING_MODE_AUTO          0x1
>> +#define STEERING_MODE_RSS           0x2
>>     // Used by the devide for returning to the driver the supported
>> steering modes
>>   struct virtio_net_steering_modes {
>> @@ -4035,6 +4036,7 @@ le32 command;
>>     // A union which can be used for passing structures to one of the sub
>> modes
>>       union {
>> +    struct virtio_net_rss rss_conf;
>>       }
>>   };
>>   @@ -4074,6 +4076,113 @@ If this feature has been negotiated, the virtio
>> header has an additional
>>     This is the default steering mode, please refer to the "Automatic
>> receive steering in multiqueue" section.
>>   +\subparagraph{Receive Side Scaling}{Device Types / Network Device /
>> Device Operation / Control Virtqueue / Steering mode / Receive Side Scaling}
>> +
>> +\begin{lstlisting}
>> +#define RSS_HASH_FUNCTION_TOEPLITZ  0x1
>> +#define RSS_HASH_FUNCTION_SYMMETRIC 0x2
>> +
>> +// Hash function fields
>> +#define RSS_HASH_FIELDS_IPV4          0x00000100
>> +#define RSS_HASH_FIELDS_TCP_IPV4      0x00000200
>> +#define RSS_HASH_FIELDS_IPV6          0x00000400
>> +#define RSS_HASH_FIELDS_IPV6_EX       0x00000800
>> +#define RSS_HASH_FIELDS_TCP_IPV6      0x00001000
>> +#define RSS_HASH_FIELDS_TCP_IPV6_EX   0x00002000
>> +
>> +struct virtio_net_rss_supported_hash{
>> +le32 hash_function;
>> +}
>> +
>> +struct virtio_net_rss {
>> +le32 hash_function;
>> +le32 hash_function_flags;
>> +le32 hash_key_length;
>> +le32 indirection_table_length;
>> +       struct {
>> +               le32 hash_key[hash_key_length];
>> +               le32 indirection_table[indirection_table_length];
>> +       }
>> +};
>> +
>> +#define VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS   0
>> +#define VIRTIO_NET_SM_CTRL_RSS_SET                       1
>> +\end{lstlisting}
>> +
>> +If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can
>> send control
>> +commands using the VIRTIO_NET_CTRL_SM_CONTROL command along with the
>> STEERING_MODE_RSS
>> +flag for configuring RSS the virtio_net_steering_mode should be filled.
>> The
>> +\field{steering_mode} field should be filled with the STEERING_MODE_RSS
>> flag along
>> +with one of the VIRTIO_NET_SM_CTRL_RSS commands in the \field{command}
>> field. The
>> +\field{rss_conf} field should be used.
>>
> May be reworded for clarify along the lines: If
> theVIRTIO_NET_F_CTRL_STEERING_MODE
> feature bit is negotiated, the driver can send steering mode control
> command,
> VIRTIO_NET_CTRL_SM_CONTROL, with the STEERING_MODE_RSSflag for configuring
> RSS provided
> it is one of the supported modes.  The supported steering modes returned
> by device in
> response to VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES command issued by the
> driver.
> For configuring particulars of RSS steering mode, the various fields of
> virtio_net_steering_mode should be filled by the driver.  This includes
> \field{steering_mode} with  STEERING_MODE_RSS flag along
> with one of the VIRTIO_NET_SM_CTRL_RSS commands in the \field{command}
> field in addition to union \field{rss_conf} field members.

Thanks for the suggestions, I'll rephrase the paragraph based on the above.

>
> +
>> +The class VIRTIO_NET_CTRL_RSS has two commands:
>> +
>> +\begin{enumerate}
>> +\item VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS returns the hash
>> functions
>> +       supported by the device to the driver.
>> +\item VIRTIO_NET_SM_CTRL_RSS_SET applies the new RSS configuration. The
>> command is
>> +       used by the driver for setting RSS hash function, hash key and
>> +       indirection table in the device.
>> +\end{enumerate}
>> +
>> +\devicenormative{\subparagraph}{Receive Side Scaling}{Device Types /
>> Network Device / Device Operation / Control Virtqueue / Steering mode /
>> Receive Side Scaling}
>> +
>> +The device MUST fill the virtio_net_rss_supported_hash structure with
>> the hash
>> +functions it supports and return the structure to the driver. One or more
>> +flags of the RSS_HASH_FUNCTION flags MUST be used to fill the
>> \field{hash_function}
>> +field.
>> +
>> +The device MUST drop all previous RSS configuration upon receiving
>> +VIRTIO_NET_SM_CTRL_RSS_SET command.
>> +
>> +The device MUST set the RSS configuration according to the settings
>> provided as
>> +follows, once the configuration process is completed the device SHOULD
>> apply
>> +the hash function to each of the incoming packets with regards to the
>> flags in
>> +the \field{hash_function_flags} fields and distribute the packets
>> through the
>> +virqueues using the calculated hash and the indirection table that were
>> earlier
>> +provided by the driver.
>> +
>> +Setting RSS configuration
>> +\begin{enumerate}
>> +\item The driver fills all of the fields and passes them through the
>> control
>> +       queue to the device.
>> +
>> +\item The device sets the RSS configuration as provided by the driver.
>> +
>> +\item If the device successfully applied the configuration, on each
>> packet
>> +       received the device MUST calculate the hash for the packet using
>> +       the fields specified in \field{hash_function_flags} and store it
>> in the
>> +       virtio-net header in the \field{hash} field and the hash fields
>> +       used in the calculation.
>> +\end{enumerate}
>> +
>> +\drivernormative{\subparagraph}{Receive Side Scaling}{Device Types /
>> Network Device / Device Operation / Control Virtqueue / Steering mode /
>> Receive Side Scaling}
>> +
>> +If the driver wants to set RSS hash it should fill the RSS structure
>> fields
>> +as follows:
>> +
>> +\begin{itemize}
>> +\item The driver SHOULD choose the hash function that SHOULD be used and
>> fill
>> +       it in the \field{hash_function} field along with the appropriate
>> flags
>> +       in the \field{hash_function_flags} field. These flags indicate to
>> the
>> +       device which packet fields MUST be used in the calculation
>> process of
>> +       the hash.
>> +\item Once the hash function has been chosen a hash key should also be
>> set by
>> +       the driver in the \field{hash_key} field, the length of the key
>> should
>> +       be stored in the \field{hash_key_length} field.
>> +\item Lastly the driver should fill the indirection table array in the
>> +       \field{indirection_table} field while setting the array length in
>> +       \field{indirection_table_length}. This structure is used by the
>> device
>> +       for determining in which RX virt queue the packet should be
>> placed.
>> +\end{itemize}
>> +Once the configuration phase is over successfully, the packets SHOULD
>> have the
>> +\field{hash} field with the hash value that was calculated by the device.
>> +
>> +Whenever the driver wants to stop performing RSS, it can switch back to
>>
> Should we say: ..stop performing RSS or any earlier configured steering
> mode,

Since this section is devoted to RSS I think we should keep this RSS
specific.

>
> +Automatic Steering Mode using the VIRTIO_NET_CTRL_SM_CONTROL command
>> along with
>> +the STEERING_MODE_AUTO flag.
>> +
>>   \paragraph{Offloads State Configuration}\label{sec:Device Types /
>> Network Device / Device Operation / Control Virtqueue / Offloads State
>> Configuration}
>>     If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the
>> driver can
>>
>
>


-- 
Respectfully,
*Sameeh Jubran*
*Linkedin <https://il.linkedin.com/pub/sameeh-jubran/87/747/a8a>*
*Software Engineer @ Daynix <http://www.daynix.com>.*

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