Skip to content

Commit

Permalink
Fix per comments
Browse files Browse the repository at this point in the history
  • Loading branch information
jimmyzhai committed Sep 4, 2024
1 parent 245ea4d commit ba0ba2f
Show file tree
Hide file tree
Showing 3 changed files with 481 additions and 16 deletions.
1 change: 0 additions & 1 deletion .wordlist.txt
Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,6 @@ configs
Conntrack
Containerlab
CP
cpus
CPUs
CreatedHalfOpenFlow
CreatedOtherFlow
Expand Down
27 changes: 16 additions & 11 deletions documentation/dataplane/dash-bmv2-data-plane-app.md
Original file line number Diff line number Diff line change
Expand Up @@ -62,9 +62,12 @@ This document only focuses on describing the design of a data-plane app example,
FLOW-DELETE hint and forwarded to data-plane app.
- Flow Age-out

In flow lookup stage, if packet hits one flow, it will refresh flow
timestamp. Data-plane app periodically scans flow table and check if flow is
timed out according to (current timestamp - flow timestamp) vs idle timeout value.
Data-plane app can help the data plane implement the flow age-out
mechanism by bridging the gap in the current data plane engine - bmv2.
For example, in flow lookup stage, if packet hits one flow, pipeline may refresh
flow timestamp via p4 extern function. Data-plane app periodically scans flow table
and check if flow is timed out according to (current timestamp - flow timestamp) vs idle
timeout value.

### 3.2. HA
- Inline flow replication
Expand Down Expand Up @@ -96,18 +99,18 @@ Refer to [SONiC DASH HLD](https://github.com/sonic-net/DASH/blob/main/documentat

![dash_dpapp_arch](images/dash-bmv2-data-plane-app-arch.drawio.svg)

Referring to the above figure, data-plane app overall is a multi-thread vpp application, running in a standalone container. It includes these components:
Referring to the above figure, data-plane app overall is a multi-thread application based on vpp, running in a standalone container. It includes these components:

- vpp master, it runs dashsai server to receive dashsai requests (dash object CRUD) via northbound RPC channel and then invoke DASH SAI APIs to handle them. The server also processes flow creation/deletion notification from vpp workers.
- vpp workers, they serve as an exception path of packet processing, running
on multi-cpus. It creates a flow in local flow table and notifies dashsai
- master thread, it runs dashsai server to receive dashsai requests (dash object CRUD) via northbound RPC channel and then invoke DASH SAI APIs to handle them. The server also processes flow creation/deletion notification from workers.
- worker threads, they serve as an exception (slow) path of packet processing, running
on multiple CPUs. It creates a flow in local flow table and notifies dashsai
server to offload it to BMv2 flow table. The packet is temporarily queued.
After workers know the success of flow offloading to BMv2, they dequeue the packet and send it back to P4 pipeline via VPP port. The workers also do flow age-out task with proper scheduling.
After workers know the success of flow offloading to BMv2, they dequeue the packet and send it back to P4 pipeline via DPAPP port. The workers also do flow age-out task with proper scheduling.
- flow table, is a local cache of BMv2 flow table.
- DASH SAI, is a unique interface for DASH object CRUD of DASH pipeline, implemented by DASH BMv2.
- VPP port, is a veth interface and connects to BMv2 via veth pair. It serves as datapath channel to receive/send all packets between date-plane app and BMv2. Generally the port supports multi RSS queues, each queue binds to one vpp worker.
- DPAPP port, is a veth interface and connects to BMv2 via veth pair. It serves as datapath channel to receive/send all packets between date-plane app and BMv2. Generally the port supports multi RSS queues, each queue binds to one worker thread.

**Note:** For simplicity and concept verification, vpp workers may directly call DASH SAI to offload flow to BMv2. The concern is that DASH SAI blocking API can block packet processing of vpp workers.
**Note:** For simplicity and concept verification, worker threads may directly call DASH SAI to offload flow to BMv2. The concern is that DASH SAI blocking API can block packet processing of workers.

## 6. Detailed design

Expand All @@ -129,7 +132,7 @@ DASH metadata records the packet processing result of DASH pipeline. It can have
When DASH pipeline requests DPAPP for flow creation, it encapsulates DASH metadata in an ethernet frame with EtherType DASH_METADATA and appends the original customer packet. The packet sent to DPAPP is like:

```
Ethernet HEADER|DASH metadata|customer packet
Ethernet HEADER | DASH metadata | customer packet
```

The number of DASH_METADATA is 0x876D, which reuses the number of EtherType SECURE_DATA (vpp/src/vnet/ethernet/types.def at master · FDio/vpp · GitHub).
Expand Down Expand Up @@ -227,6 +230,8 @@ sequenceDiagram
P->>+P: packet comes and starts flow resimulation due to eni.epoch > flow.epoch
P->>+W: slow-path, update flow data
```
Note: epoch could be an internal attribute of eni and flow, which is not
visible in public SAI.

### 6.4. HA flow
Base on basic flow, HA flow adds an extra FLOW_SYNCED state, which involves
Expand Down
Loading
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.

0 comments on commit ba0ba2f

Please sign in to comment.