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Date:      Thu, 30 May 2019 13:33:31 +0000 (UTC)
From:      Marcin Wojtas <mw@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r348405 - head/sys/dev/ena
Message-ID:  <201905301333.x4UDXV6K071650@repo.freebsd.org>
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Author: mw
Date: Thu May 30 13:33:31 2019
New Revision: 348405
URL: https://svnweb.freebsd.org/changeset/base/348405

Log:
  Add additional doorbells on ENA Tx path
  
  The new ENA HAL is introducing API, which can determine on Tx path if
  the doorbell is needed.
  
  That way, it can tell the driver, that it should call an doorbell.
  The old threshold value wasn't removed, as not all HW is supporting this
  feature - so it was reworked to also work with the new API.
  
  Submitted by:  Michal Krawczyk <mk@semihalf.com>
  Obtained from: Semihalf
  Sponsored by:  Amazon, Inc.

Modified:
  head/sys/dev/ena/ena.c
  head/sys/dev/ena/ena.h

Modified: head/sys/dev/ena/ena.c
==============================================================================
--- head/sys/dev/ena/ena.c	Thu May 30 13:31:35 2019	(r348404)
+++ head/sys/dev/ena/ena.c	Thu May 30 13:33:31 2019	(r348405)
@@ -590,6 +590,7 @@ ena_setup_tx_resources(struct ena_adapter *adapter, in
 
 	tx_ring->next_to_use = 0;
 	tx_ring->next_to_clean = 0;
+	tx_ring->acum_pkts = 0;
 
 	/* Make sure that drbr is empty */
 	ENA_RING_MTX_LOCK(tx_ring);
@@ -3007,6 +3008,18 @@ ena_xmit_mbuf(struct ena_ring *tx_ring, struct mbuf **
 
 	/* Set flags and meta data */
 	ena_tx_csum(&ena_tx_ctx, *mbuf);
+
+	if (tx_ring->acum_pkts == DB_THRESHOLD ||
+	    ena_com_is_doorbell_needed(tx_ring->ena_com_io_sq, &ena_tx_ctx)) {
+		ena_trace(ENA_DBG | ENA_TXPTH,
+		    "llq tx max burst size of queue %d achieved, writing doorbell to send burst\n",
+		    tx_ring->que->id);
+		wmb();
+		ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+		counter_u64_add(tx_ring->tx_stats.doorbells, 1);
+		tx_ring->acum_pkts = 0;
+	}
+
 	/* Prepare the packet's descriptors and send them to device */
 	rc = ena_com_prepare_tx(io_sq, &ena_tx_ctx, &nb_hw_desc);
 	if (unlikely(rc != 0)) {
@@ -3096,7 +3109,6 @@ ena_start_xmit(struct ena_ring *tx_ring)
 	struct ena_adapter *adapter = tx_ring->adapter;
 	struct ena_com_io_sq* io_sq;
 	int ena_qid;
-	int acum_pkts = 0;
 	int ret = 0;
 
 	if (unlikely((if_getdrvflags(adapter->ifp) & IFF_DRV_RUNNING) == 0))
@@ -3137,25 +3149,17 @@ ena_start_xmit(struct ena_ring *tx_ring)
 		    IFF_DRV_RUNNING) == 0))
 			return;
 
-		acum_pkts++;
+		tx_ring->acum_pkts++;
 
 		BPF_MTAP(adapter->ifp, mbuf);
-
-		if (unlikely(acum_pkts == DB_THRESHOLD)) {
-			acum_pkts = 0;
-			wmb();
-			/* Trigger the dma engine */
-			ena_com_write_sq_doorbell(io_sq);
-			counter_u64_add(tx_ring->tx_stats.doorbells, 1);
-		}
-
 	}
 
-	if (likely(acum_pkts != 0)) {
+	if (likely(tx_ring->acum_pkts != 0)) {
 		wmb();
 		/* Trigger the dma engine */
 		ena_com_write_sq_doorbell(io_sq);
 		counter_u64_add(tx_ring->tx_stats.doorbells, 1);
+		tx_ring->acum_pkts = 0;
 	}
 
 	if (unlikely(!tx_ring->running))

Modified: head/sys/dev/ena/ena.h
==============================================================================
--- head/sys/dev/ena/ena.h	Thu May 30 13:31:35 2019	(r348404)
+++ head/sys/dev/ena/ena.h	Thu May 30 13:33:31 2019	(r348405)
@@ -319,6 +319,9 @@ struct ena_ring {
 		bool running;
 	};
 
+	/* How many packets are sent in one Tx loop, used for doorbells */
+	uint32_t acum_pkts;
+
 	/* Used for LLQ */
 	uint8_t *push_buf_intermediate_buf;
 } __aligned(CACHE_LINE_SIZE);

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