On Mon, Apr 16, 2018 at 04:05:25PM +0300, Sameeh Jubran wrote:
> From: Sameeh Jubran <samee...@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 <sjub...@redhat.com>
> ---
> content.tex | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 59 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index c840588..3d538e8 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(27)] 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}
>
> @@ -4007,6 +4012,60 @@ VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command.
> The device MUST NOT queue packets on receive queues greater than
> \field{virtqueue_pairs} once it has placed the
> VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command in the used ring.
>
> +\paragraph{Steering mode}\label{sec:Device Types / Network Device / Device
> Operation / Control Virtqueue / Steering mode}
> +
> +\begin{lstlisting}
> +// steering mode flags
> +#define STEERING_MODE_AUTO 1
> +
> +struct virtio_net_steering_modes {
> +le32 steering_modes;
> +};
> +
> +struct virtio_net_steering_mode {
> +le32 steering_mode;
> +le32 command;
> +
> + union {
> + }
> +};
> +
> +#define VIRTIO_NET_F_CTRL_STEERING_MODE 27
Please use a high number (63 and down). We are running out of
low numbers it is best to keep them for things we must backport
to old virtio - such as mtu - which are required for the device
working properly.
Pls coordinate with Vlad (cc'd) who is adding a new feature too.
> +
> +#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.
> +
> \subparagraph{Legacy Interface: Automatic receive steering in multiqueue
> mode}\label{sec:Device Types / Network Device / Device Operation / Control
> Virtqueue / Automatic receive steering in multiqueue mode / Legacy Interface:
> Automatic receive steering in multiqueue mode}
> When using the legacy interface, transitional devices and drivers
> MUST format \field{virtqueue_pairs}
Please add each part where it belongs, e.g. a feature bit with other
feature bits, header field with other header fields, etc.
I think Vlad tested extending the header and found it adds
non-negligeable performance overhead. Is it worth splitting
out hash calculation? Is hash used for RX path only?
> --
> 2.13.6
>
>
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