Reduce the amount of sent RX producer notifications; from FreeBSD

diff --git a/sys/dev/pv/if_xnf.c b/sys/dev/pv/if_xnf.c
index 3580417..6131d2c 100644 (file)
--- a/sys/dev/pv/if_xnf.c
+++ b/sys/dev/pv/if_xnf.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_xnf.c,v 1.25 2016/07/29 18:31:22 mikeb Exp $       */
+/*     $OpenBSD: if_xnf.c,v 1.26 2016/07/29 18:31:51 mikeb Exp $       */
 
 /*
  * Copyright (c) 2015, 2016 Mike Belopuhov
@@ -776,21 +776,21 @@ xnf_rx_ring_fill(void *arg)
        struct xnf_rx_ring *rxr = sc->sc_rx_ring;
        bus_dmamap_t dmap;
        struct mbuf *m;
-       uint32_t cons, prod;
-       static int timer = 0;
-       int i, flags, n;
+       uint32_t cons, prod, oprod;
+       int i, flags, n, s;
+
+       s = splnet();
 
        cons = rxr->rxr_cons;
-       prod = rxr->rxr_prod;
+       prod = oprod = rxr->rxr_prod;
 
        n = if_rxr_get(&sc->sc_rx_slots, XNF_RX_DESC);
 
        /* Less than XNF_RX_MIN slots available? */
        if (n == 0 && prod - cons < XNF_RX_MIN) {
+               splx(s);
                if (ifp->if_flags & IFF_RUNNING)
-                       timeout_add(&sc->sc_rx_fill, 1 << timer);
-               if (timer < 10)
-                       timer++;
+                       timeout_add(&sc->sc_rx_fill, 10);
                return;
        }
 
@@ -803,7 +803,7 @@ xnf_rx_ring_fill(void *arg)
                        break;
                m->m_len = m->m_pkthdr.len = XNF_MCLEN;
                dmap = sc->sc_rx_dmap[i];
-               flags = (sc->sc_domid << 16) | BUS_DMA_READ |BUS_DMA_NOWAIT;
+               flags = (sc->sc_domid << 16) | BUS_DMA_READ | BUS_DMA_NOWAIT;
                if (bus_dmamap_load_mbuf(sc->sc_dmat, dmap, m, flags)) {
                        m_freem(m);
                        break;
@@ -820,7 +820,17 @@ xnf_rx_ring_fill(void *arg)
        bus_dmamap_sync(sc->sc_dmat, sc->sc_rx_rmap, 0, 0,
            BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
 
-       xen_intr_signal(sc->sc_xih);
+       if (prod - cons < XNF_RX_MIN) {
+               splx(s);
+               if (ifp->if_flags & IFF_RUNNING)
+                       timeout_add(&sc->sc_rx_fill, 10);
+               return;
+       }
+
+       if (prod - rxr->rxr_prod_event < prod - oprod)
+               xen_intr_signal(sc->sc_xih);
+
+       splx(s);
 }
 
 int