[PATCH v2 27/36] net/intel: drop unused Tx queue used count

Bruce Richardson
2026-01-13T15:19:10Z

Since drivers now track the setting of the RS bit based on fixed
thresholds rather than after a fixed number of descriptors, we no longer
need to track the number of descriptors used from one call to another.
Therefore we can remove the tx_used value in the Tx queue structure.

This value was still being used inside the IDPF splitq scalar code,
however, the ipdf driver-specific section of the Tx queue structure also
had an rs_compl_count value that was only used for the vector code
paths, so we can use it to replace the old tx_used value in the scalar
path.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
drivers/net/intel/common/tx.h | 1 -
drivers/net/intel/common/tx_scalar_fns.h | 1 -
drivers/net/intel/i40e/i40e_rxtx.c | 1 -
drivers/net/intel/iavf/iavf_rxtx.c | 1 -
drivers/net/intel/ice/ice_dcf_ethdev.c | 1 -
drivers/net/intel/ice/ice_rxtx.c | 1 -
drivers/net/intel/idpf/idpf_common_rxtx.c | 8 +++-----
drivers/net/intel/ixgbe/ixgbe_rxtx.c | 8 --------
drivers/net/intel/ixgbe/ixgbe_rxtx_vec_common.c | 1 -
9 files changed, 3 insertions(+), 20 deletions(-)

diff --git a/drivers/net/intel/common/tx.h b/drivers/net/intel/common/tx.h
index 9b3f8385e6..3976766f06 100644
--- a/drivers/net/intel/common/tx.h
+++ b/drivers/net/intel/common/tx.h
@@ -130,7 +130,6 @@ struct ci_tx_queue {
uint16_t *rs_last_id;
uint16_t nb_tx_desc; /* number of TX descriptors */
uint16_t tx_tail; /* current value of tail register */
- uint16_t nb_tx_used; /* number of TX desc used since RS bit set */
/* index to last TX descriptor to have been cleaned */
uint16_t last_desc_cleaned;
/* Total number of TX descriptors ready to be allocated. */
diff --git a/drivers/net/intel/common/tx_scalar_fns.h b/drivers/net/intel/common/tx_scalar_fns.h
index 257772a73a..3a65797c5f 100644
--- a/drivers/net/intel/common/tx_scalar_fns.h
+++ b/drivers/net/intel/common/tx_scalar_fns.h
@@ -406,7 +406,6 @@ ci_xmit_pkts(struct ci_tx_queue *txq,
m_seg = m_seg->next;
} while (m_seg);
end_pkt:
- txq->nb_tx_used = (uint16_t)(txq->nb_tx_used + nb_used);
txq->nb_tx_free = (uint16_t)(txq->nb_tx_free - nb_used);

/* Check if packet crosses into a new RS threshold bucket.
diff --git a/drivers/net/intel/i40e/i40e_rxtx.c b/drivers/net/intel/i40e/i40e_rxtx.c
index 68074333aa..812a9a7a83 100644
--- a/drivers/net/intel/i40e/i40e_rxtx.c
+++ b/drivers/net/intel/i40e/i40e_rxtx.c
@@ -2630,7 +2630,6 @@ i40e_reset_tx_queue(struct ci_tx_queue *txq)
txq->tx_next_rs = (uint16_t)(txq->tx_rs_thresh - 1);

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

txq->last_desc_cleaned = (uint16_t)(txq->nb_tx_desc - 1);
txq->nb_tx_free = (uint16_t)(txq->nb_tx_desc - 1);
diff --git a/drivers/net/intel/iavf/iavf_rxtx.c b/drivers/net/intel/iavf/iavf_rxtx.c
index b78818c02b..5227227b5a 100644
--- a/drivers/net/intel/iavf/iavf_rxtx.c
+++ b/drivers/net/intel/iavf/iavf_rxtx.c
@@ -302,7 +302,6 @@ reset_tx_queue(struct ci_tx_queue *txq)
}

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

txq->last_desc_cleaned = txq->nb_tx_desc - 1;
txq->nb_tx_free = txq->nb_tx_desc - 1;
diff --git a/drivers/net/intel/ice/ice_dcf_ethdev.c b/drivers/net/intel/ice/ice_dcf_ethdev.c
index 4ceecc15c6..02a23629d6 100644
--- a/drivers/net/intel/ice/ice_dcf_ethdev.c
+++ b/drivers/net/intel/ice/ice_dcf_ethdev.c
@@ -414,7 +414,6 @@ reset_tx_queue(struct ci_tx_queue *txq)
}

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

txq->last_desc_cleaned = txq->nb_tx_desc - 1;
txq->nb_tx_free = txq->nb_tx_desc - 1;
diff --git a/drivers/net/intel/ice/ice_rxtx.c b/drivers/net/intel/ice/ice_rxtx.c
index 0c85f9a592..3c1e1d762e 100644
--- a/drivers/net/intel/ice/ice_rxtx.c
+++ b/drivers/net/intel/ice/ice_rxtx.c
@@ -1130,7 +1130,6 @@ ice_reset_tx_queue(struct ci_tx_queue *txq)
txq->tx_next_rs = (uint16_t)(txq->tx_rs_thresh - 1);

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

txq->last_desc_cleaned = (uint16_t)(txq->nb_tx_desc - 1);
txq->nb_tx_free = (uint16_t)(txq->nb_tx_desc - 1);
diff --git a/drivers/net/intel/idpf/idpf_common_rxtx.c b/drivers/net/intel/idpf/idpf_common_rxtx.c
index 1d123f6350..b36e29c8d2 100644
--- a/drivers/net/intel/idpf/idpf_common_rxtx.c
+++ b/drivers/net/intel/idpf/idpf_common_rxtx.c
@@ -224,7 +224,6 @@ idpf_qc_split_tx_descq_reset(struct ci_tx_queue *txq)
}

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

/* Use this as next to clean for split desc queue */
txq->last_desc_cleaned = 0;
@@ -284,7 +283,6 @@ idpf_qc_single_tx_queue_reset(struct ci_tx_queue *txq)
}

txq->tx_tail = 0;
- txq->nb_tx_used = 0;

txq->last_desc_cleaned = txq->nb_tx_desc - 1;
txq->nb_tx_free = txq->nb_tx_desc - 1;
@@ -993,12 +991,12 @@ idpf_dp_splitq_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
txd->qw1.cmd_dtype |= IDPF_TXD_FLEX_FLOW_CMD_EOP;

txq->nb_tx_free = (uint16_t)(txq->nb_tx_free - nb_used);
- txq->nb_tx_used = (uint16_t)(txq->nb_tx_used + nb_used);
+ txq->rs_compl_count += nb_used;

- if (txq->nb_tx_used >= 32) {
+ if (txq->rs_compl_count >= 32) {
txd->qw1.cmd_dtype |= IDPF_TXD_FLEX_FLOW_CMD_RE;
/* Update txq RE bit counters */
- txq->nb_tx_used = 0;
+ txq->rs_compl_count = 0;
}
}

diff --git a/drivers/net/intel/ixgbe/ixgbe_rxtx.c b/drivers/net/intel/ixgbe/ixgbe_rxtx.c
index 3eeec220fd..6b8ff20f61 100644
--- a/drivers/net/intel/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/intel/ixgbe/ixgbe_rxtx.c
@@ -708,12 +708,6 @@ ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
*/
nb_used = (uint16_t)(tx_pkt->nb_segs + new_ctx);

- if (txp != NULL &&
- nb_used + txq->nb_tx_used >= txq->tx_rs_thresh)
- /* set RS on the previous packet in the burst */
- txp->read.cmd_type_len |=
- rte_cpu_to_le_32(IXGBE_TXD_CMD_RS);
-
/*
* The number of descriptors that must be allocated for a
* packet is the number of segments of that packet, plus 1
@@ -912,7 +906,6 @@ ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
* The last packet data descriptor needs End Of Packet (EOP)
*/
cmd_type_len |= IXGBE_TXD_CMD_EOP;
- txq->nb_tx_used = (uint16_t)(txq->nb_tx_used + nb_used);
txq->nb_tx_free = (uint16_t)(txq->nb_tx_free - nb_used);

/*
@@ -2551,7 +2544,6 @@ ixgbe_reset_tx_queue(struct ci_tx_queue *txq)
txq->tx_next_rs = (uint16_t)(txq->tx_rs_thresh - 1);

txq->tx_tail = 0;
- txq->nb_tx_used = 0;
/*
* Always allow 1 descriptor to be un-allocated to avoid
* a H/W race condition
diff --git a/drivers/net/intel/ixgbe/ixgbe_rxtx_vec_common.c b/drivers/net/intel/ixgbe/ixgbe_rxtx_vec_common.c
index eb7c79eaf9..63c7cb50d3 100644
--- a/drivers/net/intel/ixgbe/ixgbe_rxtx_vec_common.c
+++ b/drivers/net/intel/ixgbe/ixgbe_rxtx_vec_common.c
@@ -47,7 +47,6 @@ ixgbe_reset_tx_queue_vec(struct ci_tx_queue *txq)
txq->tx_next_rs = (uint16_t)(txq->tx_rs_thresh - 1);

txq->tx_tail = 0;
- txq->nb_tx_used = 0;
/*
* Always allow 1 descriptor to be un-allocated to avoid
* a H/W race condition
--
2.51.0