git: baa5234fbec6 - main - if_vtnet: Move the Tx interrupt threshold into the Txq structure

[Bryan Venteicher]

The branch main has been updated by bryanv:

URL: https://cgit.FreeBSD.org/src/commit/?id=baa5234fbec6befdc6c3fd7beea2f318e7e97d0c

commit baa5234fbec6befdc6c3fd7beea2f318e7e97d0c
Author:     Bryan Venteicher <bryanv at FreeBSD.org>
AuthorDate: 2021-01-19 04:55:24 +0000
Commit:     Bryan Venteicher <bryanv at FreeBSD.org>
CommitDate: 2021-01-19 04:55:24 +0000

    if_vtnet: Move the Tx interrupt threshold into the Txq structure
    
    Reviewed by: grehan (mentor)
    Differential Revision: https://reviews.freebsd.org/D27911
---
 sys/dev/virtio/network/if_vtnet.c    | 67 +++++++++++++++++-------------------
 sys/dev/virtio/network/if_vtnetvar.h |  2 +-
 2 files changed, 33 insertions(+), 36 deletions(-)

diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
index f55bd59ef749..39009a1de3f0 100644
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -140,6 +140,7 @@ static void	vtnet_rx_vq_process(struct vtnet_rxq *rxq, int tries);
 static void	vtnet_rx_vq_intr(void *);
 static void	vtnet_rxq_tq_intr(void *, int);
 
+static int	vtnet_txq_intr_threshold(struct vtnet_txq *);
 static int	vtnet_txq_below_threshold(struct vtnet_txq *);
 static int	vtnet_txq_notify(struct vtnet_txq *);
 static void	vtnet_txq_free_mbufs(struct vtnet_txq *);
@@ -219,7 +220,6 @@ static void	vtnet_set_macaddr(struct vtnet_softc *);
 static void	vtnet_attached_set_macaddr(struct vtnet_softc *);
 static void	vtnet_vlan_tag_remove(struct mbuf *);
 static void	vtnet_set_rx_process_limit(struct vtnet_softc *);
-static void	vtnet_set_tx_intr_threshold(struct vtnet_softc *);
 
 static void	vtnet_setup_rxq_sysctl(struct sysctl_ctx_list *,
 		    struct sysctl_oid_list *, struct vtnet_rxq *);
@@ -1090,7 +1090,6 @@ vtnet_setup_interface(struct vtnet_softc *sc)
 	}
 
 	vtnet_set_rx_process_limit(sc);
-	vtnet_set_tx_intr_threshold(sc);
 
 	DEBUGNET_SET(ifp, vtnet);
 
@@ -2024,15 +2023,42 @@ vtnet_rxq_tq_intr(void *xrxq, int pending)
 }
 
 static int
-vtnet_txq_below_threshold(struct vtnet_txq *txq)
+vtnet_txq_intr_threshold(struct vtnet_txq *txq)
 {
 	struct vtnet_softc *sc;
-	struct virtqueue *vq;
+	int threshold;
 
 	sc = txq->vtntx_sc;
+
+	/*
+	 * The Tx interrupt is disabled until the queue free count falls
+	 * below our threshold. Completed frames are drained from the Tx
+	 * virtqueue before transmitting new frames and in the watchdog
+	 * callout, so the frequency of Tx interrupts is greatly reduced,
+	 * at the cost of not freeing mbufs as quickly as they otherwise
+	 * would be.
+	 */
+	threshold = virtqueue_size(txq->vtntx_vq) / 4;
+
+	/*
+	 * Without indirect descriptors, leave enough room for the most
+	 * segments we handle.
+	 */
+	if ((sc->vtnet_flags & VTNET_FLAG_INDIRECT) == 0 &&
+	    threshold < sc->vtnet_tx_nsegs)
+		threshold = sc->vtnet_tx_nsegs;
+
+	return (threshold);
+}
+
+static int
+vtnet_txq_below_threshold(struct vtnet_txq *txq)
+{
+	struct virtqueue *vq;
+
 	vq = txq->vtntx_vq;
 
-	return (virtqueue_nfree(vq) <= sc->vtnet_tx_intr_thresh);
+	return (virtqueue_nfree(vq) <= txq->vtntx_intr_threshold);
 }
 
 static int
@@ -3058,6 +3084,7 @@ vtnet_init_tx_queues(struct vtnet_softc *sc)
 	for (i = 0; i < sc->vtnet_act_vq_pairs; i++) {
 		txq = &sc->vtnet_txqs[i];
 		txq->vtntx_watchdog = 0;
+		txq->vtntx_intr_threshold = vtnet_txq_intr_threshold(txq);
 #ifdef DEV_NETMAP
 		netmap_reset(NA(sc->vtnet_ifp), NR_TX, i, 0);
 #endif /* DEV_NETMAP */
@@ -3749,36 +3776,6 @@ vtnet_set_rx_process_limit(struct vtnet_softc *sc)
 	sc->vtnet_rx_process_limit = limit;
 }
 
-static void
-vtnet_set_tx_intr_threshold(struct vtnet_softc *sc)
-{
-	int size, thresh;
-
-	size = virtqueue_size(sc->vtnet_txqs[0].vtntx_vq);
-
-	/*
-	 * The Tx interrupt is disabled until the queue free count falls
-	 * below our threshold. Completed frames are drained from the Tx
-	 * virtqueue before transmitting new frames and in the watchdog
-	 * callout, so the frequency of Tx interrupts is greatly reduced,
-	 * at the cost of not freeing mbufs as quickly as they otherwise
-	 * would be.
-	 *
-	 * N.B. We assume all the Tx queues are the same size.
-	 */
-	thresh = size / 4;
-
-	/*
-	 * Without indirect descriptors, leave enough room for the most
-	 * segments we handle.
-	 */
-	if ((sc->vtnet_flags & VTNET_FLAG_INDIRECT) == 0 &&
-	    thresh < sc->vtnet_tx_nsegs)
-		thresh = sc->vtnet_tx_nsegs;
-
-	sc->vtnet_tx_intr_thresh = thresh;
-}
-
 static void
 vtnet_setup_rxq_sysctl(struct sysctl_ctx_list *ctx,
     struct sysctl_oid_list *child, struct vtnet_rxq *rxq)
diff --git a/sys/dev/virtio/network/if_vtnetvar.h b/sys/dev/virtio/network/if_vtnetvar.h
index 4189bb4d966f..82dd2514472d 100644
--- a/sys/dev/virtio/network/if_vtnetvar.h
+++ b/sys/dev/virtio/network/if_vtnetvar.h
@@ -112,6 +112,7 @@ struct vtnet_txq {
 #endif
 	int			 vtntx_id;
 	int			 vtntx_watchdog;
+	int			 vtntx_intr_threshold;
 	struct vtnet_txq_stats	 vtntx_stats;
 	struct taskqueue	*vtntx_tq;
 	struct task		 vtntx_intrtask;
@@ -161,7 +162,6 @@ struct vtnet_softc {
 	int			 vtnet_rx_nsegs;
 	int			 vtnet_rx_nmbufs;
 	int			 vtnet_rx_clustersz;
-	int			 vtnet_tx_intr_thresh;
 	int			 vtnet_tx_nsegs;
 	int			 vtnet_if_flags;
 	int			 vtnet_max_mtu;