anchao opened a new pull request, #7616:
URL: https://github.com/apache/incubator-nuttx/pull/7616
## Summary
net/l2/l3/l4: add support of iob offload
1. Add new config CONFIG_NET_LL_GRUARDSIZE to isolation of l2 stack, which
will benefit l3(IP) layer for multi-MAC(l2) implementation, especially in some
NICs such as celluler net driver.
new configuration options: CONFIG_NET_LL_GRUARDSIZE
CONFIG_NET_LL_GRUARDSIZE will reserved l2 buffer header size of network
buffer to isolate the L2/L3 (MAC/IP) data on network layer, which will be
beneficial to L3 network layer protocol transparent transmission and forwarding
------------------------------------------------------------
Layout of frist iob entry:
```
iob_data (aligned by CONFIG_IOB_ALIGNMENT)
|
| io_offset(CONFIG_NET_LL_GRUARDSIZE)
| |
-------------------------------------------------
iob | Reserved | io_len |
-------------------------------------------------
```
-------------------------------------------------------------
Layout of different NICs implementation:
```
iob_data (aligned by CONFIG_IOB_ALIGNMENT)
|
| io_offset(CONFIG_NET_LL_GRUARDSIZE)
| |
-------------------------------------------------
Ethernet | Reserved | ETH_HDRLEN | io_len |
---------------------------------|---------------
8021Q | Reserved | ETH_8021Q_HDRLEN | io_len |
---------------------------------|---------------
ipforward | Reserved | io_len |
-------------------------------------------------
```
--------------------------------------------------------------------
2. Support iob offload to l2 driver to avoid unnecessary memory copy
Support send/receive iob vectors directly between the NICs and l3/l4 stack
to avoid unnecessary memory copies, especially on hardware that supports
Scatter/gather, which can greatly improve performance.
new interface to support iob offload:
```
------------------------------------------
| IOB version | original |
|----------------------------------------|
| devif_iob_poll() | devif_poll() |
| ipv4_iob_input() | ipv4_input() |
| ipv6_iob_input() | ipv6_input() |
| pkt_iob_input() | pkt_input() |
| ... | ... |
------------------------------------------
```
--------------------------------------------------------------------
1> NIC hardware support Scatter/gather transfer
TX:
```
tcp_poll()/udp_poll()/pkt_poll()/...(l2/l3)
/ \
/ \
devif_poll_[l2/l3]_connections() devif_iob_send() (nocopy:udp/icmp/...)
/ \ (copy:tcp)
/ \
devif_iob_poll("NIC"_txpoll) callback() // "NIC"_txpoll
|
dev->d_iob: |
---------------
---------------
io_data iob1 | | | iob3 | |
|
\ ---------------
---------------
--------------- | --------------- |
iob0 | | | | iob2 | | | |
--------------- | --------------- |
\ | / /
\ | / /
----------------------------------------------
NICs io vector | | | | | | | | |
|
----------------------------------------------
```
RX:
```
[tcp|udp|icmp|...]ipv[4|6]_data_handler()(iob_concat/append to readahead)
|
|
[tcp|udp|icmp|...]_ipv[4|6]_input()
|
|
pkt/ipv[4/6]_iob_input()/...
|
|
NICs io vector receive(iov_base to each iobs)
```
--------------------------------------------------------------------
2> CONFIG_IOB_BUFSIZE is greater than MTU:
TX:
"(CONFIG_IOB_BUFSIZE) > (MAX_NETDEV_PKTSIZE + CONFIG_NET_GUARDSIZE +
CONFIG_NET_LL_GRUARDSIZE)"
```
tcp_poll()/udp_poll()/pkt_poll()/...(l2/l3)
/ \
/ \
devif_poll_[l2/l3]_connections() devif_iob_send() (nocopy:udp/icmp/...)
/ \ (copy:tcp)
/ \
devif_iob_poll("NIC"_txpoll) callback() // "NIC"_txpoll
|
"NIC"_send()
(dev->d_iob->io_data[CONFIG_NET_LL_GRUARDSIZE -
NET_LL_HDRLEN(dev)])
```
RX:
```
[tcp|udp|icmp|...]ipv[4|6]_data_handler()(iob_concat/append to readahead)
|
|
[tcp|udp|icmp|...]_ipv[4|6]_input()/...
|
|
pkt/ipv[4/6]_iob_input()/...
|
|
NICs io vector receive(iov_base to io_data)
```
--------------------------------------------------------------------
3> Compatible with all old flat buffer NICs
TX:
```
tcp_poll()/udp_poll()/pkt_poll()/...(l2/l3)
/ \
/ \
devif_poll_[l2/l3]_connections() devif_iob_send() (nocopy:udp/icmp/...)
/ \ (copy:tcp)
/ \
devif_iob_poll(devif_poll_callback()) devif_poll_callback() /* new
interface, gather iobs to flat buffer */
/ \
/ \
devif_poll("NIC"_txpoll) "NIC"_send()(dev->d_buf)
```
RX:
```
[tcp|udp|icmp|...]ipv[4|6]_data_handler()(iob_concat/append to readahead)
|
|
[tcp|udp|icmp|...]_ipv[4|6]_input()
|
|
pkt/ipv[4/6]_iob_input()/...
|
|
netdev_input() /* new interface, Scatter/gather flat/iob
buffer */
|
|
pkt/ipv[4|6]_input()/...
|
|
NICs io vector receive(Orignal flat buffer)
```
3. Iperf passthrough on NuttX simulator:
```
-------------------------------------------------
| Protocol | Server | Client | |
|-----------------------------------------------|
| TCP | 813 | 834 | Mbits/sec |
| TCP(Offload) | 1720 | 1100 | Mbits/sec |
| UDP | 22 | 757 | Mbits/sec |
| UDP(Offload) | 25 | 1250 | Mbits/sec |
-------------------------------------------------
```
Change-Id: I537b3f0330b4f3c859246c7003a3f38aa6266845
Signed-off-by: chao an <anc...@xiaomi.com>
## Impact
NuttX net stack
## Testing
iperf passthrough test on simulator
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