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[src/trunk]: src/sys/dev/pci add callout for re-filling RX ring - it's invoke...



details:   https://anonhg.NetBSD.org/src/rev/41218abad383
branches:  trunk
changeset: 323980:41218abad383
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Tue Jul 10 18:32:25 2018 +0000

description:
add callout for re-filling RX ring - it's invoked when the RX refill
code can't get enough buffers; fixes possible stall when the RXSTAT
interrupt arrives while no buffers are available

idea from OpenBSD if_msk.c rev. 1.131

as part of this remove the confusingly commented re-fill code from
msk_jfree() and instead just invoke the callout if needed; also
refill in msk_intr() only when running low instead of every RX intr;
this simplifies the code, and gives small RX performance boost on
my hardware (6%: ~38 MB/s -> ~40 MB/s)

tested on SK-9E22 (Yukon-2 XL rev. A3) by me, and 88E8071 (Yukon-2
Extreme rev. B0) by Jogn Halfpenny; unfortunately still doesn't
resolve the PR kern/53301 stall

diffstat:

 sys/dev/pci/if_msk.c |  127 ++++++++++++++++++++++++++------------------------
 1 files changed, 66 insertions(+), 61 deletions(-)

diffs (222 lines):

diff -r 53bd65bf5825 -r 41218abad383 sys/dev/pci/if_msk.c
--- a/sys/dev/pci/if_msk.c      Tue Jul 10 17:36:38 2018 +0000
+++ b/sys/dev/pci/if_msk.c      Tue Jul 10 18:32:25 2018 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: if_msk.c,v 1.71 2018/07/04 19:26:09 jdolecek Exp $ */
+/* $NetBSD: if_msk.c,v 1.72 2018/07/10 18:32:25 jdolecek Exp $ */
 /*     $OpenBSD: if_msk.c,v 1.79 2009/10/15 17:54:56 deraadt Exp $     */
 
 /*
@@ -52,7 +52,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_msk.c,v 1.71 2018/07/04 19:26:09 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_msk.c,v 1.72 2018/07/10 18:32:25 jdolecek Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -114,7 +114,7 @@
 void msk_init_yukon(struct sk_if_softc *);
 void msk_stop(struct ifnet *, int);
 void msk_watchdog(struct ifnet *);
-int msk_newbuf(struct sk_if_softc *, struct mbuf *, bus_dmamap_t);
+int msk_newbuf(struct sk_if_softc *, bus_dmamap_t);
 int msk_alloc_jumbo_mem(struct sk_if_softc *);
 void *msk_jalloc(struct sk_if_softc *);
 void msk_jfree(struct mbuf *, void *, size_t, void *);
@@ -131,6 +131,7 @@
 void msk_setmulti(struct sk_if_softc *);
 void msk_setpromisc(struct sk_if_softc *);
 void msk_tick(void *);
+static void msk_fill_rx_tick(void *);
 
 /* #define MSK_DEBUG 1 */
 #ifdef MSK_DEBUG
@@ -473,42 +474,30 @@
 }
 
 int
-msk_newbuf(struct sk_if_softc *sc_if, struct mbuf *m,
-         bus_dmamap_t dmamap)
+msk_newbuf(struct sk_if_softc *sc_if, bus_dmamap_t dmamap)
 {
        struct mbuf             *m_new = NULL;
        struct sk_chain         *c;
        struct msk_rx_desc      *r;
-
-       if (m == NULL) {
-               void *buf = NULL;
-
-               MGETHDR(m_new, M_DONTWAIT, MT_DATA);
-               if (m_new == NULL)
-                       return (ENOBUFS);
-
-               /* Allocate the jumbo buffer */
-               buf = msk_jalloc(sc_if);
-               if (buf == NULL) {
-                       m_freem(m_new);
-                       DPRINTFN(1, ("%s jumbo allocation failed -- packet "
-                           "dropped!\n", sc_if->sk_ethercom.ec_if.if_xname));
-                       return (ENOBUFS);
-               }
-
-               /* Attach the buffer to the mbuf */
-               m_new->m_len = m_new->m_pkthdr.len = SK_JLEN;
-               MEXTADD(m_new, buf, SK_JLEN, 0, msk_jfree, sc_if);
-       } else {
-               /*
-                * We're re-using a previously allocated mbuf;
-                * be sure to re-init pointers and lengths to
-                * default values.
-                */
-               m_new = m;
-               m_new->m_len = m_new->m_pkthdr.len = SK_JLEN;
-               m_new->m_data = m_new->m_ext.ext_buf;
+       void *buf = NULL;
+
+       MGETHDR(m_new, M_DONTWAIT, MT_DATA);
+       if (m_new == NULL)
+               return (ENOBUFS);
+
+       /* Allocate the jumbo buffer */
+       buf = msk_jalloc(sc_if);
+       if (buf == NULL) {
+               m_freem(m_new);
+               DPRINTFN(1, ("%s jumbo allocation failed -- packet "
+                   "dropped!\n", sc_if->sk_ethercom.ec_if.if_xname));
+               return (ENOBUFS);
        }
+
+       /* Attach the buffer to the mbuf */
+       m_new->m_len = m_new->m_pkthdr.len = SK_JLEN;
+       MEXTADD(m_new, buf, SK_JLEN, 0, msk_jfree, sc_if);
+
        m_adj(m_new, ETHER_ALIGN);
 
        c = &sc_if->sk_cdata.sk_rx_chain[sc_if->sk_cdata.sk_rx_prod];
@@ -697,6 +686,11 @@
 
        if (__predict_true(m != NULL))
                pool_cache_put(mb_cache, m);
+
+       /* Now that we know we have a free RX buffer, refill if running out */
+       if ((sc->sk_ethercom.ec_if.if_flags & IFF_RUNNING) != 0
+           && sc->sk_cdata.sk_rx_cnt < (MSK_RX_RING_CNT/3))
+               callout_schedule(&sc->sk_tick_rx, 0);
 }
 
 int
@@ -1202,6 +1196,9 @@
        callout_setfunc(&sc_if->sk_tick_ch, msk_tick, sc_if);
        callout_schedule(&sc_if->sk_tick_ch, hz);
 
+       callout_init(&sc_if->sk_tick_rx, 0);
+       callout_setfunc(&sc_if->sk_tick_rx, msk_fill_rx_tick, sc_if);
+
        /*
         * Call MI attach routines.
         */
@@ -1250,6 +1247,9 @@
        callout_halt(&sc_if->sk_tick_ch, NULL);
        callout_destroy(&sc_if->sk_tick_ch);
 
+       callout_halt(&sc_if->sk_tick_rx, NULL);
+       callout_destroy(&sc_if->sk_tick_rx);
+
        /* Detach any PHYs we might have. */
        if (LIST_FIRST(&sc_if->sk_mii.mii_phys) != NULL)
                mii_detach(&sc_if->sk_mii, MII_PHY_ANY, MII_OFFSET_ANY);
@@ -1954,31 +1954,12 @@
            total_len > ETHER_MAX_LEN_JUMBO ||
            msk_rxvalid(sc, rxstat, total_len) == 0) {
                ifp->if_ierrors++;
-               msk_newbuf(sc_if, m, dmamap);
+               m_freem(m);
                return;
        }
 
-       /*
-        * Try to allocate a new jumbo buffer. If that fails, copy the
-        * packet to mbufs and put the jumbo buffer back in the ring
-        * so it can be re-used. If allocating mbufs fails, then we
-        * have to drop the packet.
-        */
-       if (msk_newbuf(sc_if, NULL, dmamap) == ENOBUFS) {
-               struct mbuf             *m0;
-               m0 = m_devget(mtod(m, char *) - ETHER_ALIGN,
-                   total_len + ETHER_ALIGN, 0, ifp, NULL);
-               msk_newbuf(sc_if, m, dmamap);
-               if (m0 == NULL) {
-                       ifp->if_ierrors++;
-                       return;
-               }
-               m_adj(m0, ETHER_ALIGN);
-               m = m0;
-       } else {
-               m_set_rcvif(m, ifp);
-               m->m_pkthdr.len = m->m_len = total_len;
-       }
+       m_set_rcvif(m, ifp);
+       m->m_pkthdr.len = m->m_len = total_len;
 
        /* pass it on. */
        if_percpuq_enqueue(ifp->if_percpuq, m);
@@ -2047,11 +2028,35 @@
 {
        /* Make sure to not completely wrap around */
        while (sc_if->sk_cdata.sk_rx_cnt < (MSK_RX_RING_CNT - 1)) {
-               if (msk_newbuf(sc_if, NULL,
+               if (msk_newbuf(sc_if,
                    sc_if->sk_cdata.sk_rx_jumbo_map) == ENOBUFS) {
-                       break;
+                       goto schedretry;
                }
        }
+
+       return;
+
+schedretry:
+       /* Try later */
+       callout_schedule(&sc_if->sk_tick_rx, hz/2);
+}
+
+static void
+msk_fill_rx_tick(void *xsc_if)
+{
+       struct sk_if_softc *sc_if = xsc_if;
+       int s, rx_prod;
+
+       KASSERT(KERNEL_LOCKED_P());     /* XXXSMP */
+
+       s = splnet();
+       rx_prod = sc_if->sk_cdata.sk_rx_prod;
+       msk_fill_rx_ring(sc_if);
+       if (rx_prod != sc_if->sk_cdata.sk_rx_prod) {
+               SK_IF_WRITE_2(sc_if, 0, SK_RXQ1_Y2_PREF_PUTIDX,
+                   sc_if->sk_cdata.sk_rx_prod);
+       }
+       splx(s);
 }
 
 void
@@ -2136,9 +2141,8 @@
                        sc_if = sc->sk_if[cur_st->sk_link & 0x01];
                        msk_rxeof(sc_if, letoh16(cur_st->sk_len),
                            letoh32(cur_st->sk_status));
-                       msk_fill_rx_ring(sc_if);
-                       SK_IF_WRITE_2(sc_if, 0, SK_RXQ1_Y2_PREF_PUTIDX,
-                           sc_if->sk_cdata.sk_rx_prod);
+                       if (sc_if->sk_cdata.sk_rx_cnt < (MSK_RX_RING_CNT/3))
+                               msk_fill_rx_tick(sc_if);
                        break;
                case SK_Y2_STOPC_TXSTAT:
                        if (sc_if0)
@@ -2471,6 +2475,7 @@
        DPRINTFN(2, ("msk_stop\n"));
 
        callout_stop(&sc_if->sk_tick_ch);
+       callout_stop(&sc_if->sk_tick_rx);
 
        ifp->if_flags &= ~(IFF_RUNNING|IFF_OACTIVE);
 



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