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Subject: [PATCH v2 05/11] transport-fabrics: introduce Keyed Transmission
Keyed transmission is used for message oriented communication(Ex RDMA),
also add virtio-blk read/write 8K example.
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
transport-fabrics.tex | 178 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 178 insertions(+)
diff --git a/transport-fabrics.tex b/transport-fabrics.tex
index c02cf26..7711321 100644
--- a/transport-fabrics.tex
+++ b/transport-fabrics.tex
@@ -317,3 +317,181 @@ \subsubsection{Buffer Mapping Definition}\label{sec:Virtio Transport Options / V
|......|
+------+ -> 8193
\end{lstlisting}
+
+\paragraph{Keyed Transmission}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Keyed Transmission}
+Command and Segment Descriptors are transmitted in a message within a
+connection, and buffer is transmitted by remote memory access. The layout in message:
+
+\begin{lstlisting}
+CMDx contains 0 descriptor, CMDy contains (n - m + 1) descriptors:
+
+ +-----+ +-----++-----+ +-----+
+ ... | CMDx| ... | CMDy||DESCm| ... |DESCn| ...
+ +-----+ +-----++-----+ +-----+
+
+COMPx contains 0 descriptor, COMPy contains 0 descriptor:
+
+ +-----+ +-----+
+ ... |COMPx| ... |COMPy| ...
+ +-----+ +-----+
+\end{lstlisting}
+
+An example of a virtio-blk write 8K request(message size: sizeof(Command) +
+4 * sizeof(Descriptor)):
+\begin{lstlisting}
+ COMMAND +------+
+ |opcode| -> virtio_of_op_vring
+ +------+
+ |cmd id| -> 10
+ +------+
+ |length| -> 0
+ +------+
+ |ndesc | -> 4
+ +------+
+ |rsvd |
+ +------+
+
+ DESC0 +------+
+ |addr | -> 0xffff012345670000
+ +------+
+ |length| -> 16 (virtio blk write command)
+ +------+
+ |id | -> 0
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED
+ +------+
+ |key | -> 0x1234
+ +------+
+
+ DESC1 +------+
+ |addr | -> 0xffff012345671000
+ +------+
+ |length| -> 4096
+ +------+
+ |id | -> 1
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED
+ +------+
+ |key | -> 0x1236
+ +------+
+
+ DESC2 +------+
+ |addr | -> 0xffff012345673000
+ +------+
+ |length| -> 4096
+ +------+
+ |id | -> 2
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED
+ +------+
+ |key | -> 0x1238
+ +------+
+
+ DESC3 +------+
+ |addr | -> 0xffff012345677000
+ +------+
+ |length| -> 1
+ +------+
+ |id | -> 3
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED | VIRTIO_OF_DESC_F_WRITE
+ +------+
+ |key | -> 0x1239
+ +------+
+\end{lstlisting}
+
+The target handles Command, reads the remote addresses of DESC0/DESC1/DESC2,
+writes the remote address of DESC3, then responses Completion:
+\begin{lstlisting}
+ COMPLETION +------+
+ |status| -> VIRTIO_OF_SUCCESS
+ +------+
+ |cmd id| -> 10
+ +------+
+ |ndesc | -> 0
+ +------+
+ |rsvd |
+ +------+
+ |value | -> 1 (value.u32)
+ +------+
+\end{lstlisting}
+
+Another example of a virtio-blk read 8K request(message size: sizeof(Command) +
+4 * sizeof(Descriptor)):
+\begin{lstlisting}
+ COMMAND +------+
+ |opcode| -> virtio_of_op_vring
+ +------+
+ |cmd id| -> 10
+ +------+
+ |length| -> 0
+ +------+
+ |ndesc | -> 4
+ +------+
+ |rsvd |
+ +------+
+
+ DESC0 +------+
+ |addr | -> 0xffff012345670000
+ +------+
+ |length| -> 16 (virtio blk write command)
+ +------+
+ |id | -> 0
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED
+ +------+
+ |key | -> 0x1234
+ +------+
+
+ DESC1 +------+
+ |addr | -> 0xffff012345671000
+ +------+
+ |length| -> 4096
+ +------+
+ |id | -> 1
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED | VIRTIO_OF_DESC_F_WRITE
+ +------+
+ |key | -> 0x1236
+ +------+
+
+ DESC2 +------+
+ |addr | -> 0xffff012345673000
+ +------+
+ |length| -> 4096
+ +------+
+ |id | -> 2
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED | VIRTIO_OF_DESC_F_WRITE
+ +------+
+ |key | -> 0x1238
+ +------+
+
+ DESC3 +------+
+ |addr | -> 0xffff012345677000
+ +------+
+ |length| -> 1
+ +------+
+ |id | -> 3
+ +------+
+ |flags | -> VIRTIO_OF_DESC_F_KEYED | VIRTIO_OF_DESC_F_WRITE
+ +------+
+ |key | -> 0x1239
+ +------+
+\end{lstlisting}
+
+The target handles Command, reads the remote address of DESC0, writes the remote
+addresses of DESC1/DESC2/DESC3, then responses Completion:
+\begin{lstlisting}
+ COMPLETION +------+
+ |status| -> VIRTIO_OF_SUCCESS
+ +------+
+ |cmd id| -> 10
+ +------+
+ |ndesc | -> 0
+ +------+
+ |rsvd |
+ +------+
+ |value | -> 8193 (value.u32)
+ +------+
+\end{lstlisting}
--
2.25.1
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