NBSNEBIUS-65: add RDMA read/write sequence diagrams

doc/rdma/architecture.md

@@ -1,4 +1,7 @@
 # RDMA architecture
+## Read/Write sequence
+![Read/Write Sequence](diagrams/rw_sequence.svg)
+
 ## [RDMA library](../../cloud/blockstore/libs/rdma)
 
 RDMA library provides interface to communicate
@@ -9,10 +12,10 @@ and `Server`. It allows multiple Clients to connect to a single Server.
 
 Single client object (created using `NRdma::CreateClient`) can connect to multiple
 servers using `StartEndpoint`. After successful connection `Endpoint` can be
-used to allocate request (`AllocateRequest`) and sending it (`SendRequest`).
+used to allocate request (`AllocateRequest`) and send it (`SendRequest`).
 
 Each endpoint pre-allocates `QueueDepth` buffers for request/response
-metadata. Additional buffers for request/response data is allocated on demand
+metadata. Additional buffers for request/response data are allocated on demand
 using `SendBuffers` or `RecvBuffers` buffer pools kept for each endpoint.
 
 Calling `AllocateRequest` on endpoint will allocate enough buffers for the
@@ -75,12 +78,12 @@ connections. Once connection is established the rdma_target will handle
 `Read/WriteDeviceBlocksRequest`.
 
 For `WriteDeviceBlocksRequest`, it constructs `WriteBlocksRequest` using the
-same data buffers and writes data using `StorageAdaptor`.
+same data buffers and writes data using `StorageAdapter`.
 
-For `ReadDeviceBlocksRequest`, it uses `StorageAdaptor` to read data into
+For `ReadDeviceBlocksRequest`, it uses `StorageAdapter` to read data into
 `ReadBlocksRequest` and then converts response to `ReadDeviceBlocksRequest`.
 
-There is extra buffer copy inside the `StorageAdaptor`. We use aio for
-read/write and it require page_size aligned buffers. When we call
+There is extra buffer copy inside the `StorageAdapter`. We use aio for
+read/write and it requires page_size aligned buffers. When we call
 `device->Read/WriteBlocks`, the device will allocate aligned buffer, and copy
 data to/from it.

doc/rdma/diagrams/build_diagrams.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# see https://github.com/mermaid-js/mermaid-cli for installation instructions
+
+set -x
+
+mmdc -i rw_sequence.mmd -o rw_sequence.svg

doc/rdma/diagrams/rw_sequence.mmd

@@ -0,0 +1,23 @@
+sequenceDiagram
+    box Blockstore Server
+    participant P as Partition
+    participant C as Rdma Client
+    end
+    box Disk Agent
+    participant S as Rdma Server
+    participant T as Rdma Target
+    end
+
+    Note over P: Receive<br/>Read/WriteBlocksRequest
+    P-->>C: Searialize<br/>Read/WriteDeviceBlocksRequest<br/>(WRITE: COPY DATA BUFFER)
+    C->>S: IBV_WR_SEND<br/>(HEADER)
+    S->>C: IBV_WR_RDMA_READ<br/>(READ: MSG, WRITE: MSG + DATA)
+    S-->>T: Deserialize<br/>Read/WriteDeviceBlocksRequest
+    Note over T: Construct<br/>Read/WriteBlocksRequest
+    Note over T: AIO Read/Write<br/>(COPY DATA BUFFER)
+    Note over T: Read/WriteBlocksResponse
+    T-->>S: Serialize<br/>Read/WriteDeviceBlocksResponse
+    S->>C: IBV_WR_RDMA_WRITE<br/>(READ: MSG + DATA, WRITE: MSG)
+    S->>C: IBV_WR_SEND<br/>(HEADER)
+    C-->>P: Deserialize<br/>Read/WriteDeviceBlocksResponse<br/>(READ: COPY DATA BUFFER)
+    Note over P: Complete<br/>Read/WriteBlocksResponse