From: Fiona Trahe <fiona.trahe@intel.com>
Date: Wed, 15 Jan 2020 14:32:08 +0000 (+0100)
Subject: common/qat: remove tail write coalescing
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=6cde900bd59d;p=dpdk.git

common/qat: remove tail write coalescing

The feature Coalescing Tail Writes on Enqueue is removed
as it is not thread-safe and a dual-thread feature will be added shortly.

Signed-off-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Arek Kusztal <arkadiuszx.kusztal@intel.com>
---

diff --git a/drivers/common/qat/qat_qp.c b/drivers/common/qat/qat_qp.c
index 03f11f869e..01ddce0088 100644
--- a/drivers/common/qat/qat_qp.c
+++ b/drivers/common/qat/qat_qp.c
@@ -538,7 +538,6 @@ static inline void
 txq_write_tail(struct qat_qp *qp, struct qat_queue *q) {
 	WRITE_CSR_RING_TAIL(qp->mmap_bar_addr, q->hw_bundle_number,
 			q->hw_queue_number, q->tail);
-	q->nb_pending_requests = 0;
 	q->csr_tail = q->tail;
 }
 
@@ -622,25 +621,20 @@ qat_enqueue_op_burst(void *qp, void **ops, uint16_t nb_ops)
 kick_tail:
 	queue->tail = tail;
 	tmp_qp->stats.enqueued_count += nb_ops_sent;
-	queue->nb_pending_requests += nb_ops_sent;
-	if (tmp_qp->inflights16 < QAT_CSR_TAIL_FORCE_WRITE_THRESH ||
-		    queue->nb_pending_requests > QAT_CSR_TAIL_WRITE_THRESH) {
-		txq_write_tail(tmp_qp, queue);
-	}
+	txq_write_tail(tmp_qp, queue);
 	return nb_ops_sent;
 }
 
 uint16_t
 qat_dequeue_op_burst(void *qp, void **ops, uint16_t nb_ops)
 {
-	struct qat_queue *rx_queue, *tx_queue;
+	struct qat_queue *rx_queue;
 	struct qat_qp *tmp_qp = (struct qat_qp *)qp;
 	uint32_t head;
 	uint32_t resp_counter = 0;
 	uint8_t *resp_msg;
 
 	rx_queue = &(tmp_qp->rx_q);
-	tx_queue = &(tmp_qp->tx_q);
 	head = rx_queue->head;
 	resp_msg = (uint8_t *)rx_queue->base_addr + rx_queue->head;
 
@@ -677,11 +671,7 @@ qat_dequeue_op_burst(void *qp, void **ops, uint16_t nb_ops)
 						QAT_CSR_HEAD_WRITE_THRESH)
 			rxq_free_desc(tmp_qp, rx_queue);
 	}
-	/* also check if tail needs to be advanced */
-	if (tmp_qp->inflights16 <= QAT_CSR_TAIL_FORCE_WRITE_THRESH &&
-		tx_queue->tail != tx_queue->csr_tail) {
-		txq_write_tail(tmp_qp, tx_queue);
-	}
+
 	return resp_counter;
 }
 
diff --git a/drivers/common/qat/qat_qp.h b/drivers/common/qat/qat_qp.h
index 980c2ba323..9212ca457b 100644
--- a/drivers/common/qat/qat_qp.h
+++ b/drivers/common/qat/qat_qp.h
@@ -11,10 +11,6 @@ struct qat_pci_device;
 
 #define QAT_CSR_HEAD_WRITE_THRESH 32U
 /* number of requests to accumulate before writing head CSR */
-#define QAT_CSR_TAIL_WRITE_THRESH 32U
-/* number of requests to accumulate before writing tail CSR */
-#define QAT_CSR_TAIL_FORCE_WRITE_THRESH 256U
-/* number of inflights below which no tail write coalescing should occur */
 
 typedef int (*build_request_t)(void *op,
 		uint8_t *req, void *op_cookie,
@@ -64,8 +60,6 @@ struct qat_queue {
 	uint32_t	csr_tail;		/* last written tail value */
 	uint16_t	nb_processed_responses;
 	/* number of responses processed since last CSR head write */
-	uint16_t	nb_pending_requests;
-	/* number of requests pending since last CSR tail write */
 };
 
 struct qat_qp {