Am 2022-03-18 13:10, schrieb Horatiu Vultur:
The 03/18/2022 12:07, Michael Walle wrote:
> Currently when injecting or extracting a frame from CPU, the frame
> is given to the HW each word at a time. There is another way to
> inject/extract frames from CPU using FDMA(Frame Direct Memory Access).
> In this way the entire frame is given to the HW. This improves both
> RX and TX bitrate.
I wanted to test this. ping and such works fine and I'm also
seeing fdma interrupts.
Thanks for testing this also on your board.
But as soon as I try iperf3 I get a skb_panic
(due to frame size?). Hope that splash below helps.
I have not seen this issue. But it looks like it is a problem that
there
is no more space to add the FCS.
Can you tell me how you run iperf3 so I can also try it?
oh, I forgot to include the commandline.
# on the remote computer
$ iperf3 --version
iperf 3.6 (cJSON 1.5.2)
Linux eddie01 4.19.0-18-686-pae #1 SMP Debian 4.19.208-1 (2021-09-29)
i686
Optional features available: CPU affinity setting, IPv6 flow label,
SCTP, TCP congestion algorithm setting, sendfile / zerocopy, socket
pacing, authentication
$ iperf3 -s
# on the board
$ iperf3 --version
iperf 3.10.1 (cJSON 1.7.13)
Linux buildroot 5.17.0-rc8-next-20220316-00058-gc6cb0628f2a6-dirty #385
SMP Fri Mar 18 13:34:26 CET 2022 armv7l
Optional features available: CPU affinity setting, IPv6 flow label, TCP
congestion algorithm setting, sendfile / zerocopy, socket pacing, bind
to device, support IPv4 don't fragment
$ iperf3 -c eddie01
Also I have a small diff that might fix the issue:
---
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
@@ -534,6 +534,8 @@ int lan966x_fdma_xmit(struct sk_buff *skb, __be32
*ifh, struct net_device *dev)
struct lan966x_tx_dcb *next_dcb, *dcb;
struct lan966x_tx *tx = &lan966x->tx;
struct lan966x_db *next_db;
+ int needed_headroom;
+ int needed_tailroom;
dma_addr_t dma_addr;
int next_to_use;
int err;
@@ -554,10 +556,11 @@ int lan966x_fdma_xmit(struct sk_buff *skb,
__be32 *ifh, struct net_device *dev)
/* skb processing */
skb_tx_timestamp(skb);
btw. skb_tx_timestamp() should be as close to the handover
of the frame to the hardware as possible, no?
- if (skb_headroom(skb) < IFH_LEN * sizeof(u32)) {
- err = pskb_expand_head(skb,
- IFH_LEN * sizeof(u32) -
skb_headroom(skb),
- 0, GFP_ATOMIC);
+ needed_headroom = max_t(int, IFH_LEN * sizeof(u32) -
skb_headroom(skb), 0);
+ needed_tailroom = max_t(int, ETH_FCS_LEN - skb_tailroom(skb),
0);
+ if (needed_headroom || needed_tailroom) {
+ err = pskb_expand_head(skb, needed_headroom,
needed_tailroom,
+ GFP_ATOMIC);
if (unlikely(err)) {
dev->stats.tx_dropped++;
err = NETDEV_TX_OK;
Indeed this will fix the issue:
# iperf3 -c eddie01
Connecting to host eddie01, port 5201
[ 5] local 10.0.1.143 port 55342 connected to 10.0.1.42 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.01 sec 43.8 MBytes 364 Mbits/sec 0 245 KBytes
[ 5] 1.01-2.02 sec 43.8 MBytes 364 Mbits/sec 0 246 KBytes
[ 5] 2.02-3.03 sec 43.8 MBytes 364 Mbits/sec 0 259 KBytes
# iperf3 -R -c eddie01
Connecting to host eddie01, port 5201
Reverse mode, remote host eddie01 is sending
[ 5] local 10.0.1.143 port 55346 connected to 10.0.1.42 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 28.6 MBytes 240 Mbits/sec
[ 5] 1.00-2.00 sec 28.9 MBytes 242 Mbits/sec
[ 5] 2.00-3.00 sec 28.7 MBytes 241 Mbits/sec
-michael
