net/l2/l3/l4: add support of iob offload
1. Add new config CONFIG_NET_LL_GUARDSIZE 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_GUARDSIZE
CONFIG_NET_LL_GUARDSIZE 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_GUARDSIZE)
| |
-------------------------------------------------
iob | Reserved | io_len |
-------------------------------------------------
-------------------------------------------------------------
Layout of different NICs implementation:
iob_data (aligned by CONFIG_IOB_ALIGNMENT)
|
| io_offset(CONFIG_NET_LL_GUARDSIZE)
| |
-------------------------------------------------
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() |
| ... | ... |
------------------------------------------
--------------------------------------------------------------------
1> NIC hardware support Scatter/gather transfer
TX:
tcp_poll()/udp_poll()/pkt_poll()/...(l3|l4)
/ \
/ \
devif_poll_[l3|l4]_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]_in()/...
|
|
pkt/ipv[4/6]_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_GUARDSIZE)"
tcp_poll()/udp_poll()/pkt_poll()/...(l3|l4)
/ \
/ \
devif_poll_[l3|l4]_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_GUARDSIZE - NET_LL_HDRLEN(dev)])
RX:
[tcp|udp|icmp|...]ipv[4|6]_data_handler()(iob_concat/append to readahead)
|
|
[tcp|udp|icmp|...]_ipv[4|6]_in()/...
|
|
pkt/ipv[4/6]_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()/...(l3|l4)
/ \
/ \
devif_poll_[l3|l4]_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]_in()/...
|
|
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 |
-------------------------------------------------
Signed-off-by: chao an <anchao@xiaomi.com>
34d2cde8a8