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Subject: [PATCH v2 04/11] transport-fabrics: introduce Stream Transmission
Stream transmission is used for stream oriented communication(Ex TCP),
also add virtio-blk read/write 8K example.
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
transport-fabrics.tex | 229 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 229 insertions(+)
diff --git a/transport-fabrics.tex b/transport-fabrics.tex
index b88acfd..c02cf26 100644
--- a/transport-fabrics.tex
+++ b/transport-fabrics.tex
@@ -88,3 +88,232 @@ \subsubsection{Segment Descriptor Definition}\label{sec:Virtio Transport Options
\end{tabular}
Depending on the opcode, a Command contains zero or more structure virtio_of_vring_desc.
+
+\subsubsection{Buffer Mapping Definition}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Buffer Mapping Definition}
+Virtio Over Fabrics defines two types of buffer mapping rules.
+
+\paragraph{Stream Transmission}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Stream Transmission}
+Command, Segment Descriptors, and buffer are transmitted in a stream within a
+connection. The layout in stream:
+
+\begin{lstlisting}
+CMDx contains 0 descriptor, CMDy contains (n - m + 1) descriptors and buffer:
+
+ +-----+ +-----++-----+ +-----++-----+
+ ... | CMDx| ... | CMDy||DESCm| ... |DESCn|| BUF | ...
+ +-----+ +-----++-----+ +-----++-----+
+
+COMPx contains 0 descriptor, COMPy contains (k - j + 1) descriptors and buffer:
+
+ +-----+ +-----++-----+ +-----++-----+
+ ... |COMPx| ... |COMPy||DESCj| ... |DESCk|| BUF | ...
+ +-----+ +-----++-----+ +-----++-----+
+\end{lstlisting}
+
+An example of a virtio-blk write 8K request(total size: sizeof(Command) +
+4 * sizeof(Descriptor) + 8208):
+\begin{lstlisting}
+ COMMAND +------+
+ |opcode| -> virtio_of_op_vring
+ +------+
+ |cmd id| -> 10
+ +------+
+ |length| -> 8208
+ +------+
+ |ndesc | -> 4
+ +------+
+ |rsvd |
+ +------+
+
+ DESC0 +------+
+ +-----|addr | -> 0
+ | +------+
+ | |length| -> 16 (virtio blk write command)
+ | +------+
+ | |id | -> 0
+ | +------+
+ | |flags | -> 0
+ | +------+
+ |
+ DESC1 | +------+
+ | +---|addr | -> 16
+ | | +------+
+ | | |length| -> 4096
+ | | +------+
+ | | |id | -> 1
+ | | +------+
+ | | |flags | -> 0
+ | | +------+
+ | |
+ DESC2 | | +------+
+ | | +-|addr | -> 4112
+ | | | +------+
+ | | | |length| -> 4096
+ | | | +------+
+ | | | |id | -> 2
+ | | | +------+
+ | | | |flags | -> 0
+ | | | +------+
+ | | |
+ DESC3 | | | +------+
+ | | | |addr | -> 0
+ | | | +------+
+ | | | |length| -> 1
+ | | | +------+
+ | | | |id | -> 3
+ | | | +------+
+ | | | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | | | +------+
+ | | |
+ DATA +-+-+>+------+ -> 0
+ | | |......|
+ +-+>+------+ -> 16
+ | |......|
+ +>+------+ -> 4112
+ |......|
+ +------+ -> 8208
+\end{lstlisting}
+
+The Completion of this request(total size: sizeof(Completion) +
+1 * sizeof(Descriptor) + 1):
+\begin{lstlisting}
+ COMPLETION +------+
+ |status| -> VIRTIO_OF_SUCCESS
+ +------+
+ |cmd id| -> 10
+ +------+
+ |ndesc | -> 1
+ +------+
+ |rsvd |
+ +------+
+ |value | -> 1 (value.u32)
+ +------+
+
+ DESC0 +------+
+ +-|addr | -> 0
+ | +------+
+ | |length| -> 1
+ | +------+
+ | |id | -> 3
+ | +------+
+ | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | +------+
+ |
+ DATA |>+------+ -> 0
+ |......|
+ +------+ -> 1
+\end{lstlisting}
+
+Another example of a virtio-blk read 8K request(total size: sizeof(Command) +
+4 * sizeof(Descriptor) + 16):
+\begin{lstlisting}
+ COMMAND +------+
+ |opcode| -> virtio_of_op_vring
+ +------+
+ |cmd id| -> 14
+ +------+
+ |length| -> 16 (virtio blk read command)
+ +------+
+ |ndesc | -> 4
+ +------+
+ |rsvd |
+ +------+
+
+ DESC0 +------+
+ +-|addr | -> 0
+ | +------+
+ | |length| -> 16
+ | +------+
+ | |id | -> 0
+ | +------+
+ | |flags | -> 0
+ | +------+
+ |
+ DESC1 | +------+
+ | |addr | -> 0
+ | +------+
+ | |length| -> 4096
+ | +------+
+ | |id | -> 1
+ | +------+
+ | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | +------+
+ |
+ DESC2 | +------+
+ | |addr | -> 0
+ | +------+
+ | |length| -> 4096
+ | +------+
+ | |id | -> 2
+ | +------+
+ | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | +------+
+ |
+ DESC3 | +------+
+ | |addr | -> 0
+ | +------+
+ | |length| -> 1
+ | +------+
+ | |id | -> 3
+ | +------+
+ | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | +------+
+ |
+ DATA +>+------+ -> 0
+ |......|
+ +------+ -> 16
+\end{lstlisting}
+
+The Completion of this request(total size: sizeof(Completion) +
+3 * sizeof(Descriptor) + 8193):
+\begin{lstlisting}
+ COMPLETION +------+
+ |status| -> VIRTIO_OF_SUCCESS
+ +------+
+ |cmd id| -> 14
+ +------+
+ |ndesc | -> 3
+ +------+
+ |rsvd |
+ +------+
+ |value | -> 8193 (value.u32)
+ +------+
+
+ DESC0 +------+
+ +-----|addr | -> 0
+ | +------+
+ | |length| -> 4096
+ | +------+
+ | |id | -> 1
+ | +------+
+ | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | +------+
+ |
+ DESC1 | +------+
+ | +---|addr | -> 4096
+ | | +------+
+ | | |length| -> 4096
+ | | +------+
+ | | |id | -> 2
+ | | +------+
+ | | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | | +------+
+ | |
+ DESC2 | | +------+
+ | | +-|addr | -> 8192
+ | | | +------+
+ | | | |length| -> 1
+ | | | +------+
+ | | | |id | -> 3
+ | | | +------+
+ | | | |flags | -> VIRTIO_OF_DESC_F_WRITE
+ | | | +------+
+ | | |
+ DATA +-+-+>+------+ -> 0
+ | | |......|
+ +-+>+------+ -> 4096
+ | |......|
+ +>+------+ -> 8192
+ |......|
+ +------+ -> 8193
+\end{lstlisting}
--
2.25.1
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