Amber-lite NIC's TX rate limiting has large deviations for small
packets. To fix this issue, there are some changes:
1. Set TDM_RL_ADJ (0x1820c) to 21B (includes 7B Ethernet preamble,
1B SFD, 1B EFD, and 12B IPG).
2) Remove the rate offset in the driver (e.g., 105 / 100, a rough
compensation value from Linux kernel driver tests).
After these changes, accuracy deviation for 64B packets is within
~5%, while large packets show lower deviation.
Fixes: a309ab43acf3 ("net/txgbe: support Tx queue rate limiting for Amber-Lite")
Cc: [email protected]
Signed-off-by: Zaiyu Wang <[email protected]>
---
drivers/net/txgbe/base/txgbe_regs.h | 1 +
drivers/net/txgbe/txgbe_ethdev.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/txgbe/base/txgbe_regs.h
b/drivers/net/txgbe/base/txgbe_regs.h
index 95c585a025..060757323a 100644
--- a/drivers/net/txgbe/base/txgbe_regs.h
+++ b/drivers/net/txgbe/base/txgbe_regs.h
@@ -1670,6 +1670,7 @@ enum txgbe_5tuple_protocol {
#define TXGBE_TDM_FACTOR_INT_SHIFT 16
#define TXGBE_TDM_FACTOR_FRA_SHIFT 2
+#define TXGBE_TDM_RL_ADJ 0x1820C
#define TXGBE_TDM_RL_VM_IDX 0x018218
#define TXGBE_TDM_RL_VM_CFG 0x01821C
#define TXGBE_TDM_RL_CFG 0x018400
diff --git a/drivers/net/txgbe/txgbe_ethdev.c b/drivers/net/txgbe/txgbe_ethdev.c
index 779874aac9..414107d7a7 100644
--- a/drivers/net/txgbe/txgbe_ethdev.c
+++ b/drivers/net/txgbe/txgbe_ethdev.c
@@ -4314,7 +4314,6 @@ txgbe_set_queue_rate_limit(struct rte_eth_dev *dev,
u16 frac;
link_speed = dev->data->dev_link.link_speed;
- tx_rate = tx_rate * 105 / 100;
/* Calculate the rate factor values to set */
factor_int = link_speed / tx_rate;
frac = (link_speed % tx_rate) * 10000 / tx_rate;
@@ -4324,6 +4323,7 @@ txgbe_set_queue_rate_limit(struct rte_eth_dev *dev,
factor_fra = 0;
}
+ wr32(hw, TXGBE_TDM_RL_ADJ, 21);
wr32(hw, TXGBE_TDM_RL_QUEUE_IDX, queue_idx);
wr32m(hw, TXGBE_TDM_RL_QUEUE_CFG,
TXGBE_TDM_FACTOR_INT_MASK, factor_int <<
TXGBE_TDM_FACTOR_INT_SHIFT);
--
2.21.0.windows.1
