Enable Launch Time Control (LTC) support to XDP zero copy via XDP Tx
metadata framework.
This patch is tested with tools/testing/selftests/bpf/xdp_hw_metadata on
Intel Tiger Lake platform. Below are the test steps and result.
Test Steps:
1. Add mqprio qdisc:
$ sudo tc qdisc add dev enp2s0 handle 8001: parent root mqprio num_tc 4
map 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 1@1 1@2 1@3 hw 0
2. Enable launch time hardware offload on hardware queue 1:
$ sudo tc qdisc replace dev enp2s0 parent 8001:2 etf offload clockid
CLOCK_TAI delta 500000
3. Change RSS to route all incoming IP packets into hardware queue 1:
$ sudo ethtool -X enp2s0 start 1 equal 1
4. Start xdp_hw_metadata selftest application:
$ sudo ./xdp_hw_metadata enp2s0 -l 1000000000
5. Send an UDP packet to port 9091 of DUT.
$ echo -n xdp | nc -u -q0 169.254.1.1 9091
When launch time is set to 1s in the future, the delta between launch time
and transmit hardware timestamp is equal to 0.016us, as shown in result
below:
0x562ff5dc8880: rx_desc[4]->addr=84110 addr=84110 comp_addr=84110 EoP
rx_hash: 0xE343384 with RSS type:0x1
HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to User RX-time
sec:0.0002 (183.103 usec)
XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User
RX-time sec:0.0001 (80.309 usec)
No rx_vlan_tci or rx_vlan_proto, err=-95
0x562ff5dc8880: ping-pong with csum=561c (want c7dd) csum_start=34
csum_offset=6
HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW
Launch-time sec:1.0000 (1000000.000 usec)
0x562ff5dc8880: complete tx idx=4 addr=4018
HW Launch-time: 1734578016467548904 (sec:1734578016.4675) delta to HW
TX-complete-time sec:0.0000 (0.016 usec)
HW TX-complete-time: 1734578016467548920 (sec:1734578016.4675) delta to
User TX-complete-time sec:0.0000 (32.546 usec)
XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User
TX-complete-time sec:0.9999 (999929.768 usec)
HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW
TX-complete-time sec:1.0000 (1000000.016 usec)
0x562ff5dc8880: complete rx idx=132 addr=84110
Signed-off-by: Song Yoong Siang <yoong.siang.s...@intel.com>
---
drivers/net/ethernet/intel/igc/igc_main.c | 78 ++++++++++++++++-------
1 file changed, 56 insertions(+), 22 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
b/drivers/net/ethernet/intel/igc/igc_main.c
index 27872bdea9bd..6857f5f5b4b2 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter
*adapter, struct sk_buff *s
return false;
}
+static void igc_insert_empty_packet(struct igc_ring *tx_ring)
+{
+ struct igc_tx_buffer *empty_info;
+ struct sk_buff *empty;
+ void *data;
+
+ empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
+ empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
+ if (!empty)
+ return;
+
+ data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
+ memset(data, 0, IGC_EMPTY_FRAME_SIZE);
+
+ igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
+
+ if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
+ dev_kfree_skb_any(empty);
+}
+
static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
struct igc_ring *tx_ring)
{
@@ -1603,26 +1623,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff
*skb,
skb->tstamp = ktime_set(0, 0);
launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag,
&insert_empty);
- if (insert_empty) {
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
-
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
- goto done;
-
- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
-
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
-
- if (igc_init_tx_empty_descriptor(tx_ring,
- empty,
- empty_info) < 0)
- dev_kfree_skb_any(empty);
- }
+ if (insert_empty)
+ igc_insert_empty_packet(tx_ring);
done:
/* record the location of the first descriptor for this packet */
@@ -2955,9 +2957,33 @@ static u64 igc_xsk_fill_timestamp(void *_priv)
return *(u64 *)_priv;
}
+static void igc_xsk_request_launch_time(u64 launch_time, void *_priv)
+{
+ struct igc_metadata_request *meta_req = _priv;
+ struct igc_ring *tx_ring = meta_req->tx_ring;
+ __le32 launch_time_offset;
+ bool insert_empty = false;
+ bool first_flag = false;
+
+ if (!tx_ring->launchtime_enable)
+ return;
+
+ launch_time_offset = igc_tx_launchtime(tx_ring,
+ ns_to_ktime(launch_time),
+ &first_flag, &insert_empty);
+ if (insert_empty) {
+ igc_insert_empty_packet(tx_ring);
+ meta_req->tx_buffer =
+ &tx_ring->tx_buffer_info[tx_ring->next_to_use];
+ }
+
+ igc_tx_ctxtdesc(tx_ring, launch_time_offset, first_flag, 0, 0, 0);
+}
+
const struct xsk_tx_metadata_ops igc_xsk_tx_metadata_ops = {
.tmo_request_timestamp = igc_xsk_request_timestamp,
.tmo_fill_timestamp = igc_xsk_fill_timestamp,
+ .tmo_request_launch_time = igc_xsk_request_launch_time,
};
static void igc_xdp_xmit_zc(struct igc_ring *ring)
@@ -2980,7 +3006,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
ntu = ring->next_to_use;
budget = igc_desc_unused(ring);
- while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
+ while (xsk_tx_peek_desc(pool, &xdp_desc) && budget >= 4) {
struct igc_metadata_request meta_req;
struct xsk_tx_metadata *meta = NULL;
struct igc_tx_buffer *bi;
@@ -3004,6 +3030,12 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
xsk_tx_metadata_request(meta, &igc_xsk_tx_metadata_ops,
&meta_req);
+ /* xsk_tx_metadata_request() may have updated next_to_use */
+ ntu = ring->next_to_use;
+
+ /* xsk_tx_metadata_request() may have updated Tx buffer info */
+ bi = meta_req.tx_buffer;
+
tx_desc = IGC_TX_DESC(ring, ntu);
tx_desc->read.cmd_type_len = cpu_to_le32(meta_req.cmd_type);
tx_desc->read.olinfo_status = cpu_to_le32(olinfo_status);
@@ -3021,9 +3053,11 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
ntu++;
if (ntu == ring->count)
ntu = 0;
+
+ ring->next_to_use = ntu;
+ budget = igc_desc_unused(ring);
}
- ring->next_to_use = ntu;
if (tx_desc) {
igc_flush_tx_descriptors(ring);
xsk_tx_release(pool);
--
2.34.1
