Use hardware timer to simulate interrupt moderation. Old devices will no

longer be livelocked when they are receiving on GigE line.  Newer devices
also gain well controlled interrupt rate.

If hardware supports interrupt moderation (e.g. 8168B, 8168C), you could
also use hardware based interrupt moderation, however, due to lack of
necessary information it does not work as reliably as simulated interrupt
moderation.  It is _not_ recommended currently.

By default, PCIe devices' simulated interrupt moderation timer is set to
75us, while PCI devices' is set to 125us.

From sephe@DragonFly

2 files changed, 245 insertions, 98 deletions

diff --git a/sys/dev/ic/re.c b/sys/dev/ic/re.c
index 6bf35a4e446..c1b54c09189 100644
--- a/sys/dev/ic/re.c
+++ b/sys/dev/ic/re.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: re.c,v 1.93 2008/10/09 23:02:07 brad Exp $	*/
+/*	$OpenBSD: re.c,v 1.94 2008/10/11 23:49:05 brad Exp $	*/
 /*	$FreeBSD: if_re.c,v 1.31 2004/09/04 07:54:05 ru Exp $	*/
 /*
  * Copyright (c) 1997, 1998-2003
@@ -165,8 +165,8 @@ int	re_encap(struct rl_softc *, struct mbuf *, int *);
 int	re_newbuf(struct rl_softc *, int, struct mbuf *);
 int	re_rx_list_init(struct rl_softc *);
 int	re_tx_list_init(struct rl_softc *);
-void	re_rxeof(struct rl_softc *);
-void	re_txeof(struct rl_softc *);
+int	re_rxeof(struct rl_softc *);
+int	re_txeof(struct rl_softc *);
 void	re_tick(void *);
 void	re_start(struct ifnet *);
 int	re_ioctl(struct ifnet *, u_long, caddr_t);
@@ -188,6 +188,13 @@ void	re_miibus_statchg(struct device *);
 void	re_iff(struct rl_softc *);
 void	re_reset(struct rl_softc *);
 
+void	re_setup_hw_im(struct rl_softc *);
+void	re_setup_sim_im(struct rl_softc *);
+void	re_disable_hw_im(struct rl_softc *);
+void	re_disable_sim_im(struct rl_softc *);
+void	re_config_imtype(struct rl_softc *, int);
+void	re_setup_intr(struct rl_softc *, int, int);
+
 #ifdef RE_DIAG
 int	re_diag(struct rl_softc *);
 #endif
@@ -799,6 +806,40 @@ re_attach(struct rl_softc *sc, const char *intrstr)
 
 	sc->sc_hwrev = CSR_READ_4(sc, RL_TXCFG) & RL_TXCFG_HWREV;
 
+	sc->rl_tx_time = 5;		/* 125us */
+	sc->rl_rx_time = 2;		/* 50us */
+	if (sc->rl_flags & RL_FLAG_PCIE)
+		sc->rl_sim_time = 75;	/* 75us */
+	else
+		sc->rl_sim_time = 125;	/* 125us */
+	sc->rl_imtype = RL_IMTYPE_SIM;	/* simulated interrupt moderation */
+
+	if (sc->sc_hwrev == RL_HWREV_8139CPLUS)
+		sc->rl_bus_speed = 33; /* XXX */
+	else if (sc->rl_flags & RL_FLAG_PCIE)
+		sc->rl_bus_speed = 125;
+	else {
+		u_int8_t cfg2;
+
+		cfg2 = CSR_READ_1(sc, RL_CFG2);
+		switch (cfg2 & RL_CFG2_PCI_MASK) {
+		case RL_CFG2_PCI_33MHZ:
+ 			sc->rl_bus_speed = 33;
+			break;
+		case RL_CFG2_PCI_66MHZ:
+			sc->rl_bus_speed = 66;
+			break;
+		default:
+			printf("%s: unknown bus speed, assume 33MHz\n",
+			    sc->sc_dev.dv_xname);
+			sc->rl_bus_speed = 33;
+			break;
+		}
+
+		if (cfg2 & RL_CFG2_PCI_64BIT)
+			sc->rl_flags |= RL_FLAG_PCI64;
+	}
+
 	switch (sc->sc_hwrev) {
 	case RL_HWREV_8139CPLUS:
 		sc->rl_flags |= RL_FLAG_NOJUMBO;
@@ -819,13 +860,14 @@ re_attach(struct rl_softc *sc, const char *intrstr)
 	case RL_HWREV_8168_SPIN2:
 	case RL_HWREV_8168_SPIN3:
 		sc->rl_flags |= RL_FLAG_INVMAR | RL_FLAG_PHYWAKE |
-		    RL_FLAG_MACSTAT;
+		    RL_FLAG_MACSTAT | RL_FLAG_HWIM;
 		break;
 	case RL_HWREV_8168C:
 	case RL_HWREV_8168C_SPIN2:
 	case RL_HWREV_8168CP:
 		sc->rl_flags |= RL_FLAG_INVMAR | RL_FLAG_PHYWAKE |
-		    RL_FLAG_PAR | RL_FLAG_DESCV2 | RL_FLAG_MACSTAT;
+		    RL_FLAG_PAR | RL_FLAG_DESCV2 | RL_FLAG_MACSTAT |
+		    RL_FLAG_HWIM;
 		/*
 		 * These controllers support jumbo frame but it seems
 		 * that enabling it requires touching additional magic
@@ -848,6 +890,8 @@ re_attach(struct rl_softc *sc, const char *intrstr)
 		break;
 	}
 
+	re_config_imtype(sc, sc->rl_imtype);
+
 	if (sc->rl_flags & RL_FLAG_PAR) {
 		/*
 		 * XXX Should have a better way to extract station
@@ -923,32 +967,6 @@ re_attach(struct rl_softc *sc, const char *intrstr)
 	printf(", %s, address %s\n", intrstr,
 	    ether_sprintf(sc->sc_arpcom.ac_enaddr));
 
-	if (sc->sc_hwrev == RL_HWREV_8139CPLUS) {
-		sc->rl_bus_speed = 33; /* XXX */
-	} else if (sc->rl_flags & RL_FLAG_PCIE) {
-		sc->rl_bus_speed = 125;
-	} else {
-		u_int8_t cfg2;
-
-		cfg2 = CSR_READ_1(sc, RL_CFG2);
-		switch (cfg2 & RL_CFG2_PCI_MASK) {
-		case RL_CFG2_PCI_33MHZ:
-			sc->rl_bus_speed = 33;
-			break;
-		case RL_CFG2_PCI_66MHZ:
-			sc->rl_bus_speed = 66;
-			break;
-		default:
-			printf("%s: unknown bus speed, assume 33MHz\n",
-			    sc->sc_dev.dv_xname);
-			sc->rl_bus_speed = 33;
-			break;
-		}
-
-		if (cfg2 & RL_CFG2_PCI_64BIT)
-			sc->rl_flags |= RL_FLAG_PCI64;
-	}
-
 	if (sc->rl_ldata.rl_tx_desc_cnt >
 	    PAGE_SIZE / sizeof(struct rl_desc)) {
 		sc->rl_ldata.rl_tx_desc_cnt =
@@ -1285,12 +1303,12 @@ re_rx_list_init(struct rl_softc *sc)
  * the reception of jumbo frames that have been fragmented
  * across multiple 2K mbuf cluster buffers.
  */
-void
+int
 re_rxeof(struct rl_softc *sc)
 {
 	struct mbuf	*m;
 	struct ifnet	*ifp;
-	int		i, total_len;
+	int		i, total_len, rx = 0;
 	struct rl_desc	*cur_rx;
 	struct rl_rxsoft *rxs;
 	u_int32_t	rxstat, rxvlan;
@@ -1309,6 +1327,7 @@ re_rxeof(struct rl_softc *sc)
 		total_len = rxstat & sc->rl_rxlenmask;
 		rxs = &sc->rl_ldata.rl_rxsoft[i];
 		m = rxs->rxs_mbuf;
+		rx = 1;
 
 		/* Invalidate the RX mbuf and unload its map */
 
@@ -1451,15 +1470,17 @@ re_rxeof(struct rl_softc *sc)
 	}
 
 	sc->rl_ldata.rl_rx_prodidx = i;
+
+	return (rx);
 }
 
-void
+int
 re_txeof(struct rl_softc *sc)
 {
 	struct ifnet	*ifp;
 	struct rl_txq	*txq;
 	uint32_t	txstat;
-	int		idx, descidx;
+	int		idx, descidx, tx = 0;
 
 	ifp = &sc->sc_arpcom.ac_if;
 
@@ -1481,6 +1502,7 @@ re_txeof(struct rl_softc *sc)
 		if (txstat & RL_TDESC_CMD_OWN)
 			break;
 
+		tx = 1;
 		sc->rl_ldata.rl_tx_free += txq->txq_nsegs;
 		KASSERT(sc->rl_ldata.rl_tx_free <= RL_TX_DESC_CNT(sc));
 		bus_dmamap_sync(sc->sc_dmat, txq->txq_dmamap,
@@ -1502,25 +1524,19 @@ re_txeof(struct rl_softc *sc)
 	if (sc->rl_ldata.rl_tx_free > RL_NTXDESC_RSVD)
 		ifp->if_flags &= ~IFF_OACTIVE;
 
-	if (sc->rl_ldata.rl_tx_free < RL_TX_DESC_CNT(sc)) {
-		/*
-		 * Some chips will ignore a second TX request issued while an
-		 * existing transmission is in progress. If the transmitter goes
-		 * idle but there are still packets waiting to be sent, we need
-		 * to restart the channel here to flush them out. This only
-		 * seems to be required with the PCIe devices.
-		 */
+	/*
+	 * Some chips will ignore a second TX request issued while an
+	 * existing transmission is in progress. If the transmitter goes
+	 * idle but there are still packets waiting to be sent, we need
+	 * to restart the channel here to flush them out. This only
+	 * seems to be required with the PCIe devices.
+	 */
+	if (sc->rl_ldata.rl_tx_free < RL_TX_DESC_CNT(sc))
 		CSR_WRITE_1(sc, sc->rl_txstart, RL_TXSTART_START);
-
-		/*
-		 * If not all descriptors have been released reaped yet,
-		 * reload the timer so that we will eventually get another
-		 * interrupt that will cause us to re-enter this routine.
-		 * This is done in case the transmitter has gone idle.
-		 */
-		CSR_WRITE_4(sc, RL_TIMERCNT, 1);
-	} else
+	else
 		ifp->if_timer = 0;
+
+	return (tx);
 }
 
 void
@@ -1559,13 +1575,14 @@ re_intr(void *arg)
 	struct rl_softc	*sc = arg;
 	struct ifnet	*ifp;
 	u_int16_t	status;
-	int		claimed = 0;
+	int		claimed = 0, rx, tx;
 
 	ifp = &sc->sc_arpcom.ac_if;
 
-	if (!(ifp->if_flags & IFF_UP))
+	if (!(ifp->if_flags & IFF_RUNNING))
 		return (0);
 
+	rx = tx = 0;
 	for (;;) {
 
 		status = CSR_READ_2(sc, RL_ISR);
@@ -1578,14 +1595,13 @@ re_intr(void *arg)
 		if ((status & RL_INTRS_CPLUS) == 0)
 			break;
 
-		if (status & (RL_ISR_RX_OK | RL_ISR_RX_ERR)) {
-			re_rxeof(sc);
+		if (status & (sc->rl_rx_ack | RL_ISR_RX_ERR)) {
+			rx |= re_rxeof(sc);
 			claimed = 1;
 		}
 
-		if (status & (RL_ISR_TIMEOUT_EXPIRED | RL_ISR_TX_ERR |
-		    RL_ISR_TX_DESC_UNAVAIL)) {
-			re_txeof(sc);
+		if (status & (sc->rl_tx_ack | RL_ISR_TX_ERR)) {
+			tx |= re_txeof(sc);
 			claimed = 1;
 		}
 
@@ -1602,7 +1618,17 @@ re_intr(void *arg)
 		}
 	}
 
-	if (claimed && !IFQ_IS_EMPTY(&ifp->if_snd))
+	if (sc->rl_imtype == RL_IMTYPE_SIM) {
+		if ((sc->rl_flags & RL_FLAG_TIMERINTR)) {
+			if ((tx | rx) == 0)
+				re_setup_intr(sc, 1, RL_IMTYPE_NONE);
+			else
+				CSR_WRITE_4(sc, RL_TIMERCNT, 1); /* reload */
+		} else if (tx | rx)
+			re_setup_intr(sc, 1, RL_IMTYPE_SIM);
+	}
+
+	if (tx && !IFQ_IS_EMPTY(&ifp->if_snd))
 		re_start(ifp);
 
 	return (claimed);
@@ -1852,27 +1878,14 @@ re_start(struct ifnet *ifp)
 #endif
 	}
 
-	if (queued == 0) {
-		if (sc->rl_ldata.rl_tx_free != RL_TX_DESC_CNT(sc))
-			CSR_WRITE_4(sc, RL_TIMERCNT, 1);
+	if (queued == 0)
 		return;
-	}
 
 	sc->rl_ldata.rl_txq_prodidx = idx;
 
 	CSR_WRITE_1(sc, sc->rl_txstart, RL_TXSTART_START);
 
 	/*
-	 * Use the countdown timer for interrupt moderation.
-	 * 'TX done' interrupts are disabled. Instead, we reset the
-	 * countdown timer, which will begin counting until it hits
-	 * the value in the TIMERINT register, and then trigger an
-	 * interrupt. Each time we write to the TIMERCNT register,
-	 * the timer count is reset to 0.
-	 */
-	CSR_WRITE_4(sc, RL_TIMERCNT, 1);
-
-	/*
 	 * Set a timeout in case the chip goes out to lunch.
 	 */
 	ifp->if_timer = 5;
@@ -1990,8 +2003,8 @@ re_init(struct ifnet *ifp)
 	if (sc->rl_testmode)
 		CSR_WRITE_2(sc, RL_IMR, 0);
 	else
-		CSR_WRITE_2(sc, RL_IMR, RL_INTRS_CPLUS);
-	CSR_WRITE_2(sc, RL_ISR, RL_INTRS_CPLUS);
+		re_setup_intr(sc, 1, sc->rl_imtype);
+	CSR_WRITE_2(sc, RL_ISR, sc->rl_imtype);
 
 	/* Start RX/TX process. */
 	CSR_WRITE_4(sc, RL_MISSEDPKT, 0);
@@ -2001,24 +2014,6 @@ re_init(struct ifnet *ifp)
 #endif
 
 	/*
-	 * Initialize the timer interrupt register so that
-	 * a timer interrupt will be generated once the timer
-	 * reaches a certain number of ticks. The timer is
-	 * reloaded on each transmit. This gives us TX interrupt
-	 * moderation, which dramatically improves TX frame rate.
-	 */
-	if (sc->sc_hwrev == RL_HWREV_8139CPLUS)
-		CSR_WRITE_4(sc, RL_TIMERINT, 0x400);
-	else {
-		/*
-		 * Set hardware timer to 125us
-		 * XXX measurement showed me the actual value is ~76us,
-		 * which is ~2/3 of the desired value
-		 */
-		CSR_WRITE_4(sc, RL_TIMERINT_8169, 125 * sc->rl_bus_speed);
-	}
-
-	/*
 	 * For 8169 gigE NICs, set the max allowed RX packet
 	 * size so we can receive jumbo frames.
 	 */
@@ -2169,7 +2164,7 @@ re_stop(struct ifnet *ifp, int disable)
 	sc = ifp->if_softc;
 
 	ifp->if_timer = 0;
-	sc->rl_flags &= ~RL_FLAG_LINK;
+	sc->rl_flags &= ~(RL_FLAG_LINK|RL_FLAG_TIMERINTR);
 
 	timeout_del(&sc->timer_handle);
 	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
@@ -2205,3 +2200,134 @@ re_stop(struct ifnet *ifp, int disable)
 		}
 	}
 }
+
+void
+re_setup_hw_im(struct rl_softc *sc)
+{
+	KASSERT(sc->rl_flags & RL_FLAG_HWIM);
+
+	/*
+	 * Interrupt moderation
+	 *
+	 * 0xABCD
+	 * A - unknown (maybe TX related)
+	 * B - TX timer (unit: 25us)
+	 * C - unknown (maybe RX related)
+	 * D - RX timer (unit: 25us)
+	 *
+	 *
+	 * re(4)'s interrupt moderation is actually controlled by
+	 * two variables, like most other NICs (bge, bnx etc.)
+	 * o  timer
+	 * o  number of packets [P]
+	 *
+	 * The logic relationship between these two variables is
+	 * similar to other NICs too:
+	 * if (timer expire || packets > [P])
+	 *     Interrupt is delivered
+	 *
+	 * Currently we only know how to set 'timer', but not
+	 * 'number of packets', which should be ~30, as far as I
+	 * tested (sink ~900Kpps, interrupt rate is 30KHz)
+	 */
+	CSR_WRITE_2(sc, RL_IM,
+		    RL_IM_RXTIME(sc->rl_rx_time) |
+		    RL_IM_TXTIME(sc->rl_tx_time) |
+		    RL_IM_MAGIC);
+}
+
+void
+re_disable_hw_im(struct rl_softc *sc)
+{
+	if (sc->rl_flags & RL_FLAG_HWIM)
+		CSR_WRITE_2(sc, RL_IM, 0);
+}
+
+void
+re_setup_sim_im(struct rl_softc *sc)
+{
+	if (sc->sc_hwrev == RL_HWREV_8139CPLUS)
+		CSR_WRITE_4(sc, RL_TIMERINT, 0x400); /* XXX */
+	else {
+		u_int32_t ticks;
+
+		/*
+		 * Datasheet says tick decreases at bus speed,
+		 * but it seems the clock runs a little bit
+		 * faster, so we do some compensation here.
+		 */
+		ticks = (sc->rl_sim_time * sc->rl_bus_speed * 8) / 5;
+		CSR_WRITE_4(sc, RL_TIMERINT_8169, ticks);
+	}
+	CSR_WRITE_4(sc, RL_TIMERCNT, 1); /* reload */
+	sc->rl_flags |= RL_FLAG_TIMERINTR;
+}
+
+void
+re_disable_sim_im(struct rl_softc *sc)
+{
+	if (sc->sc_hwrev == RL_HWREV_8139CPLUS)
+		CSR_WRITE_4(sc, RL_TIMERINT, 0);
+	else 
+		CSR_WRITE_4(sc, RL_TIMERINT_8169, 0);
+	sc->rl_flags &= ~RL_FLAG_TIMERINTR;
+}
+
+void
+re_config_imtype(struct rl_softc *sc, int imtype)
+{
+	switch (imtype) {
+	case RL_IMTYPE_HW:
+		KASSERT(sc->rl_flags & RL_FLAG_HWIM);
+		/* FALL THROUGH */
+	case RL_IMTYPE_NONE:
+		sc->rl_intrs = RL_INTRS_CPLUS;
+		sc->rl_rx_ack = RL_ISR_RX_OK | RL_ISR_FIFO_OFLOW |
+				RL_ISR_RX_OVERRUN;
+		sc->rl_tx_ack = RL_ISR_TX_OK;
+		break;
+
+	case RL_IMTYPE_SIM:
+		sc->rl_intrs = RL_INTRS_TIMER;
+		sc->rl_rx_ack = RL_ISR_TIMEOUT_EXPIRED;
+		sc->rl_tx_ack = RL_ISR_TIMEOUT_EXPIRED;
+		break;
+
+	default:
+		panic("%s: unknown imtype %d\n",
+		      sc->sc_dev.dv_xname, imtype);
+	}
+}
+
+void
+re_setup_intr(struct rl_softc *sc, int enable_intrs, int imtype)
+{
+	re_config_imtype(sc, imtype);
+
+	if (enable_intrs)
+		CSR_WRITE_2(sc, RL_IMR, sc->rl_intrs);
+	else
+		CSR_WRITE_2(sc, RL_IMR, 0); 
+
+	switch (imtype) {
+	case RL_IMTYPE_NONE:
+		re_disable_sim_im(sc);
+		re_disable_hw_im(sc);
+		break;
+
+	case RL_IMTYPE_HW:
+		KASSERT(sc->rl_flags & RL_FLAG_HWIM);
+		re_disable_sim_im(sc);
+		re_setup_hw_im(sc);
+		break;
+
+	case RL_IMTYPE_SIM:
+		re_disable_hw_im(sc);
+		re_setup_sim_im(sc);
+		break;
+
+	default:
+		panic("%s: unknown imtype %d\n",
+		      sc->sc_dev.dv_xname, imtype);
+	}
+}
diff --git a/sys/dev/ic/rtl81x9reg.h b/sys/dev/ic/rtl81x9reg.h
index 9fed4d864db..11aeffbc04b 100644
--- a/sys/dev/ic/rtl81x9reg.h
+++ b/sys/dev/ic/rtl81x9reg.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtl81x9reg.h,v 1.55 2008/10/06 00:34:10 brad Exp $	*/
+/*	$OpenBSD: rtl81x9reg.h,v 1.56 2008/10/11 23:49:05 brad Exp $	*/
 
 /*
  * Copyright (c) 1997, 1998
@@ -234,9 +234,13 @@
 
 #define RL_INTRS_CPLUS	\
 	(RL_ISR_RX_OK|RL_ISR_RX_ERR|RL_ISR_TX_ERR|			\
-	RL_ISR_RX_OVERRUN|RL_ISR_PKT_UNDERRUN|RL_ISR_FIFO_OFLOW|	\
-	RL_ISR_PCS_TIMEOUT|RL_ISR_SYSTEM_ERR|RL_ISR_TIMEOUT_EXPIRED)
+	RL_ISR_RX_OVERRUN|RL_ISR_FIFO_OFLOW|RL_ISR_LINKCHG|		\
+	RL_ISR_SYSTEM_ERR|RL_ISR_TX_OK)
 
+#define RL_INTRS_TIMER							\
+	(RL_ISR_RX_ERR|RL_ISR_TX_ERR|					\
+	RL_ISR_LINKCHG|RL_ISR_SYSTEM_ERR|				\
+	RL_ISR_TIMEOUT_EXPIRED)
 
 /*
  * Media status register. (8139 only)
@@ -519,6 +523,10 @@
 #define RL_RXCFG_CONFIG		(RL_RX_FIFOTHRESH|RL_RX_MAXDMA|RL_RX_BUF_SZ)
 #define RL_TXCFG_CONFIG		(RL_TXCFG_IFG|RL_TX_MAXDMA)
 
+#define RL_IM_MAGIC		0x5050
+#define RL_IM_RXTIME(t)		((t) & 0xf)
+#define RL_IM_TXTIME(t)		(((t) & 0xf) << 8)
+
 struct rl_chain_data {
 	u_int16_t		cur_rx;
 	caddr_t			rl_rx_buf;
@@ -816,7 +824,20 @@ struct rl_softc {
 #define	RL_FLAG_PAR		0x0040
 #define	RL_FLAG_DESCV2		0x0080
 #define	RL_FLAG_MACSTAT		0x0100
+#define	RL_FLAG_HWIM		0x0200
+#define	RL_FLAG_TIMERINTR	0x0400
 #define	RL_FLAG_LINK		0x8000
+
+	u_int16_t		rl_intrs;
+	u_int16_t		rl_tx_ack;
+	u_int16_t		rl_rx_ack;
+	int			rl_tx_time;
+	int			rl_rx_time;
+	int			rl_sim_time;
+	int			rl_imtype;
+#define	RL_IMTYPE_NONE		0
+#define	RL_IMTYPE_SIM		1	/* simulated */
+#define	RL_IMTYPE_HW		2	/* hardware based */
 };
 
 /*