[src/trunk]: src/sys/arch/arm/broadcom Change the way rx are consumed. Only ...

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/74916b5ac9c5
branches:  trunk
changeset: 783493:74916b5ac9c5
user:      matt <matt%NetBSD.org@localhost>
date:      Tue Dec 25 21:17:40 2012 +0000

description:
Change the way rx are consumed.  Only consume a 1/4 of the receive buffers
before refilling with new buffers.  Don't stop until there are no packets
left to receive.

diffstat:

 sys/arch/arm/broadcom/bcm53xx_eth.c |  48 +++++++++++++++++++++++++++---------
 1 files changed, 36 insertions(+), 12 deletions(-)

diffs (107 lines):

diff -r 1f34f930cfae -r 74916b5ac9c5 sys/arch/arm/broadcom/bcm53xx_eth.c
--- a/sys/arch/arm/broadcom/bcm53xx_eth.c       Tue Dec 25 20:31:03 2012 +0000
+++ b/sys/arch/arm/broadcom/bcm53xx_eth.c       Tue Dec 25 21:17:40 2012 +0000
@@ -35,7 +35,7 @@
 
 #include <sys/cdefs.h>
 
-__KERNEL_RCSID(1, "$NetBSD: bcm53xx_eth.c,v 1.19 2012/12/19 02:44:39 matt Exp $");
+__KERNEL_RCSID(1, "$NetBSD: bcm53xx_eth.c,v 1.20 2012/12/25 21:17:40 matt Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -1009,29 +1009,27 @@
 #endif
 }
 
-static void
+static bool
 bcmeth_rxq_consume(
        struct bcmeth_softc *sc,
-       struct bcmeth_rxqueue *rxq)
+       struct bcmeth_rxqueue *rxq,
+       size_t atmost)
 {
        struct ifnet * const ifp = &sc->sc_if;
        struct gmac_rxdb *consumer = rxq->rxq_consumer;
        size_t rxconsumed = 0;
+       bool didconsume = false;
 
-       for (;;) {
+       while (atmost-- > 0) {
                if (consumer == rxq->rxq_producer) {
-                       rxq->rxq_consumer = consumer;
-                       rxq->rxq_inuse -= rxconsumed;
                        KASSERT(rxq->rxq_inuse == 0);
-                       return;
+                       break;
                }
                
                uint32_t rcvsts0 = bcmeth_read_4(sc, rxq->rxq_reg_rcvsts0);
                uint32_t currdscr = __SHIFTOUT(rcvsts0, RCV_CURRDSCR);
                if (consumer == rxq->rxq_first + currdscr) {
-                       rxq->rxq_consumer = consumer;
-                       rxq->rxq_inuse -= rxconsumed;
-                       return;
+                       break;
                }
                bcmeth_rxq_desc_postsync(sc, rxq, consumer, 1);
 
@@ -1039,6 +1037,7 @@
                 * We own this packet again.  Copy the rxsts word from it.
                 */
                rxconsumed++;
+               didconsume = true;
                uint32_t rxsts;
                KASSERT(rxq->rxq_mhead != NULL);
                bus_dmamap_t map = M_GETCTX(rxq->rxq_mhead, bus_dmamap_t);
@@ -1152,6 +1151,17 @@
                        consumer = rxq->rxq_first;
                }
        }
+
+       /*
+        * Update queue info.
+        */
+       rxq->rxq_consumer = consumer;
+       rxq->rxq_inuse -= rxconsumed;
+
+       /*
+        * Did we consume anything?
+        */
+       return didconsume;
 }
 
 static void
@@ -1896,7 +1906,14 @@
                /*
                 * Let's consume 
                 */
-               bcmeth_rxq_consume(sc, &sc->sc_rxq);
+               while (bcmeth_rxq_consume(sc, &sc->sc_rxq,
+                   sc->sc_rxq.rxq_threshold / 4)) {
+                       /*
+                        * We've consumed a quarter of the ring and still have
+                        * more to do.  Refill the ring.
+                        */
+                       bcmeth_rxq_produce(sc, &sc->sc_rxq);
+               }
                intmask |= RCVINT;
        }
 
@@ -1949,7 +1966,14 @@
                /*
                 * Let's consume 
                 */
-               bcmeth_rxq_consume(sc, &sc->sc_rxq);
+               while (bcmeth_rxq_consume(sc, &sc->sc_rxq,
+                   sc->sc_rxq.rxq_threshold / 4)) {
+                       /*
+                        * We've consumed a quarter of the ring and still have
+                        * more to do.  Refill the ring.
+                        */
+                       bcmeth_rxq_produce(sc, &sc->sc_rxq);
+               }
                intmask |= RCVINT;
        }