bus_dmamap_sync the rx ring once per em_rxeof call, rather than for every

rx descriptor.

slightly tweak by matthew
tested on alpha and amd64

1 files changed, 16 insertions, 16 deletions

diff --git a/sys/dev/pci/if_em.c b/sys/dev/pci/if_em.c
index ce0adcb6e1a..8a1600cfab4 100644
--- a/sys/dev/pci/if_em.c
+++ b/sys/dev/pci/if_em.c
@@ -31,7 +31,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 ***************************************************************************/
 
-/* $OpenBSD: if_em.c,v 1.283 2014/07/08 00:17:44 dlg Exp $ */
+/* $OpenBSD: if_em.c,v 1.284 2014/07/08 02:57:27 dlg Exp $ */
 /* $FreeBSD: if_em.c,v 1.46 2004/09/29 18:28:28 mlaier Exp $ */
 
 #include <dev/pci/if_em.h>
@@ -2848,25 +2848,24 @@ em_rxeof(struct em_softc *sc)
 	struct em_buffer    *pkt;
 	u_int8_t	    status;
 
+	if (sc->rx_ndescs == 0)
+		return;
+
 	i = sc->next_rx_desc_to_check;
 
-	while (sc->rx_ndescs > 0) {
+	bus_dmamap_sync(sc->rxdma.dma_tag, sc->rxdma.dma_map,
+	    0, sizeof(*desc) * sc->num_rx_desc,
+	    BUS_DMASYNC_POSTREAD);
+
+	do {
 		m = NULL;
 
 		desc = &sc->rx_desc_base[i];
 		pkt = &sc->rx_buffer_area[i];
 
-		bus_dmamap_sync(sc->rxdma.dma_tag, sc->rxdma.dma_map,
-		    sizeof(*desc) * i, sizeof(*desc),
-		    BUS_DMASYNC_POSTREAD);
-
 		status = desc->status;
-		if (!ISSET(status, E1000_RXD_STAT_DD)) {
-			bus_dmamap_sync(sc->rxdma.dma_tag, sc->rxdma.dma_map,
-			    sizeof(*desc) * i, sizeof(*desc),
-			    BUS_DMASYNC_PREREAD);
+		if (!ISSET(status, E1000_RXD_STAT_DD))
 			break;
-		}
 
 		/* pull the mbuf off the ring */
 		bus_dmamap_sync(sc->rxtag, pkt->map, 0, pkt->map->dm_mapsize,
@@ -2988,14 +2987,15 @@ em_rxeof(struct em_softc *sc)
 			m_freem(m);
 		}
 
-		bus_dmamap_sync(sc->rxdma.dma_tag, sc->rxdma.dma_map,
-		    sizeof(*desc) * i, sizeof(*desc),
-		    BUS_DMASYNC_PREREAD);
-
 		/* Advance our pointers to the next descriptor. */
 		if (++i == sc->num_rx_desc)
 			i = 0;
-	}
+	} while (sc->rx_ndescs > 0);
+
+	bus_dmamap_sync(sc->rxdma.dma_tag, sc->rxdma.dma_map,
+	    0, sizeof(*desc) * sc->num_rx_desc,
+	    BUS_DMASYNC_PREREAD);
+
 	sc->next_rx_desc_to_check = i;
 }