[RFC PATCH 26/27] net/intel: drop unused Tx queue used count

[Bruce Richardson]

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 at 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 3d0a23eda3..27a5dafefc 100644
--- a/drivers/net/intel/common/tx_scalar_fns.h
+++ b/drivers/net/intel/common/tx_scalar_fns.h
@@ -404,7 +404,6 @@ 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 1fadd0407a..e1226d649b 100644
--- a/drivers/net/intel/i40e/i40e_rxtx.c
+++ b/drivers/net/intel/i40e/i40e_rxtx.c
@@ -2632,7 +2632,6 @@ 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 4517d55011..9cac6e8841 100644
--- a/drivers/net/intel/iavf/iavf_rxtx.c
+++ b/drivers/net/intel/iavf/iavf_rxtx.c
@@ -298,7 +298,6 @@ 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 a6a454ddf5..092981f452 100644
--- a/drivers/net/intel/ice/ice_rxtx.c
+++ b/drivers/net/intel/ice/ice_rxtx.c
@@ -1127,7 +1127,6 @@ 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