From 7480325b78dd2b3189429e53dcfacbdce7241bfb Mon Sep 17 00:00:00 2001 From: dg Date: Tue, 4 Aug 1998 08:53:12 +0000 Subject: Implemented a more sophisticated mechanism for handling transmitter interrupts which now defers them until the transmit queue if filled up with completed buffers. This has two advantages: first, it reduces the number of transmitter interrupts to just 1/120th of the rate that they occured previously, and two, running down many buffers at once has much improved cache effects. --- sys/pci/if_fxp.c | 148 ++++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 103 insertions(+), 45 deletions(-) (limited to 'sys/pci') diff --git a/sys/pci/if_fxp.c b/sys/pci/if_fxp.c index 92897c3..faf83fb 100644 --- a/sys/pci/if_fxp.c +++ b/sys/pci/if_fxp.c @@ -27,7 +27,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: if_fxp.c,v 1.53 1998/08/02 00:28:45 dg Exp $ + * $Id: if_fxp.c,v 1.54 1998/08/02 00:33:38 dg Exp $ */ /* @@ -244,6 +244,15 @@ static int tx_threshold = 64; #define FXP_NTXCB 128 /* + * Number of completed TX commands at which point an interrupt + * will be generated to garbage collect the attached buffers. + * Must be at least one less than FXP_NTXCB, and should be + * enough less so that the transmitter doesn't becomes idle + * during the buffer rundown (which would reduce performance). + */ +#define FXP_CXINT_THRESH 120 + +/* * TxCB list index mask. This is used to do list wrap-around. */ #define FXP_TXCB_MASK (FXP_NTXCB - 1) @@ -394,9 +403,10 @@ fxp_attach(parent, self, aux) */ if_attach(ifp); /* - * Let the system queue as many packets as we have TX descriptors. + * Let the system queue as many packets as we have available + * TX descriptors. */ - ifp->if_snd.ifq_maxlen = FXP_NTXCB; + ifp->if_snd.ifq_maxlen = FXP_NTXCB - 1; ether_ifattach(ifp, enaddr); #if NBPFILTER > 0 bpfattach(&sc->sc_ethercom.ec_if.if_bpf, ifp, DLT_EN10MB, @@ -566,9 +576,10 @@ fxp_attach(config_id, unit) */ if_attach(ifp); /* - * Let the system queue as many packets as we have TX descriptors. + * Let the system queue as many packets as we have available + * TX descriptors. */ - ifp->if_snd.ifq_maxlen = FXP_NTXCB; + ifp->if_snd.ifq_maxlen = FXP_NTXCB - 1; ether_ifattach(ifp); #if NBPFILTER > 0 bpfattach(ifp, DLT_EN10MB, sizeof(struct ether_header)); @@ -797,8 +808,10 @@ fxp_start(ifp) /* * We're finished if there is nothing more to add to the list or if * we're all filled up with buffers to transmit. + * NOTE: One TxCB is reserved to guarantee that fxp_mc_setup() can add + * a NOP command when needed. */ - while (ifp->if_snd.ifq_head != NULL && sc->tx_queued < FXP_NTXCB) { + while (ifp->if_snd.ifq_head != NULL && sc->tx_queued < FXP_NTXCB - 1) { struct mbuf *m, *mb_head; int segment; @@ -859,8 +872,18 @@ tbdinit: txp->tbd_number = segment; txp->mb_head = mb_head; txp->cb_status = 0; - txp->cb_command = - FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF | FXP_CB_COMMAND_S; + if (sc->tx_queued != FXP_CXINT_THRESH - 1) { + txp->cb_command = + FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF | FXP_CB_COMMAND_S; + } else { + txp->cb_command = + FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF | FXP_CB_COMMAND_S | FXP_CB_COMMAND_I; + /* + * Set a 5 second timer just in case we don't hear from the + * card again. + */ + ifp->if_timer = 5; + } txp->tx_threshold = tx_threshold; /* @@ -895,12 +918,6 @@ tbdinit: if (txp != NULL) { fxp_scb_wait(sc); CSR_WRITE_1(sc, FXP_CSR_SCB_COMMAND, FXP_SCB_COMMAND_CU_RESUME); - - /* - * Set a 5 second timer just in case we don't hear from the - * card again. - */ - ifp->if_timer = 5; } } @@ -928,6 +945,33 @@ fxp_intr(arg) CSR_WRITE_1(sc, FXP_CSR_SCB_STATACK, statack); /* + * Free any finished transmit mbuf chains. + */ + if (statack & FXP_SCB_STATACK_CXTNO) { + struct fxp_cb_tx *txp; + + for (txp = sc->cbl_first; sc->tx_queued && + (txp->cb_status & FXP_CB_STATUS_C) != 0; + txp = txp->next) { + if (txp->mb_head != NULL) { + m_freem(txp->mb_head); + txp->mb_head = NULL; + } + sc->tx_queued--; + } + sc->cbl_first = txp; + ifp->if_timer = 0; + if (sc->tx_queued == 0) { + if (sc->need_mcsetup) + fxp_mc_setup(sc); + } + /* + * Try to start more packets transmitting. + */ + if (ifp->if_snd.ifq_head != NULL) + fxp_start(ifp); + } + /* * Process receiver interrupts. If a no-resource (RNR) * condition exists, get whatever packets we can and * re-start the receiver. @@ -1003,33 +1047,6 @@ rcvloop: FXP_SCB_COMMAND_RU_START); } } - /* - * Free any finished transmit mbuf chains. - */ - if (statack & FXP_SCB_STATACK_CNA) { - struct fxp_cb_tx *txp; - - for (txp = sc->cbl_first; sc->tx_queued && - (txp->cb_status & FXP_CB_STATUS_C) != 0; - txp = txp->next) { - if (txp->mb_head != NULL) { - m_freem(txp->mb_head); - txp->mb_head = NULL; - } - sc->tx_queued--; - } - sc->cbl_first = txp; - if (sc->tx_queued == 0) { - ifp->if_timer = 0; - if (sc->need_mcsetup) - fxp_mc_setup(sc); - } - /* - * Try to start more packets transmitting. - */ - if (ifp->if_snd.ifq_head != NULL) - fxp_start(ifp); - } } #if defined(__NetBSD__) return (claimed); @@ -1262,7 +1279,7 @@ fxp_init(xsc) cbp->dma_bce = 0; /* (disable) dma max counters */ cbp->late_scb = 0; /* (don't) defer SCB update */ cbp->tno_int = 0; /* (disable) tx not okay interrupt */ - cbp->ci_int = 0; /* interrupt on CU not active */ + cbp->ci_int = 1; /* interrupt on CU idle */ cbp->save_bf = prm; /* save bad frames */ cbp->disc_short_rx = !prm; /* discard short packets */ cbp->underrun_retry = 1; /* retry mode (1) on DMA underrun */ @@ -1691,7 +1708,7 @@ fxp_ioctl(ifp, command, data) * * We have an artificial restriction that the multicast setup command * must be the first command in the chain, so we take steps to ensure - * that. By requiring this, it allows us to keep the performance of + * this. By requiring this, it allows us to keep up the performance of * the pre-initialized command ring (esp. link pointers) by not actually * inserting the mcsetup command in the ring - i.e. its link pointer * points to the TxCB ring, but the mcsetup descriptor itself is not part @@ -1709,8 +1726,49 @@ fxp_mc_setup(sc) struct ifmultiaddr *ifma; int nmcasts; + /* + * If there are queued commands, we must wait until they are all + * completed. If we are already waiting, then add a NOP command + * with interrupt option so that we're notified when all commands + * have been completed - fxp_start() ensures that no additional + * TX commands will be added when need_mcsetup is true. + */ if (sc->tx_queued) { + struct fxp_cb_tx *txp; + + /* + * need_mcsetup will be true if we are already waiting for the + * NOP command to be completed (see below). In this case, bail. + */ + if (sc->need_mcsetup) + return; sc->need_mcsetup = 1; + + /* + * Add a NOP command with interrupt so that we are notified when all + * TX commands have been processed. + */ + txp = sc->cbl_last->next; + txp->mb_head = NULL; + txp->cb_status = 0; + txp->cb_command = FXP_CB_COMMAND_NOP | FXP_CB_COMMAND_S | FXP_CB_COMMAND_I; + /* + * Advance the end of list forward. + */ + sc->cbl_last->cb_command &= ~FXP_CB_COMMAND_S; + sc->cbl_last = txp; + sc->tx_queued++; + /* + * Issue a resume in case the CU has just suspended. + */ + fxp_scb_wait(sc); + CSR_WRITE_1(sc, FXP_CSR_SCB_COMMAND, FXP_SCB_COMMAND_CU_RESUME); + /* + * Set a 5 second timer just in case we don't hear from the + * card again. + */ + ifp->if_timer = 5; + return; } sc->need_mcsetup = 0; @@ -1721,7 +1779,7 @@ fxp_mc_setup(sc) mcsp->next = sc->cbl_base; mcsp->mb_head = NULL; mcsp->cb_status = 0; - mcsp->cb_command = FXP_CB_COMMAND_MCAS | FXP_CB_COMMAND_S; + mcsp->cb_command = FXP_CB_COMMAND_MCAS | FXP_CB_COMMAND_S | FXP_CB_COMMAND_I; mcsp->link_addr = vtophys(&sc->cbl_base->cb_status); nmcasts = 0; @@ -1758,6 +1816,6 @@ fxp_mc_setup(sc) CSR_WRITE_4(sc, FXP_CSR_SCB_GENERAL, vtophys(&mcsp->cb_status)); CSR_WRITE_1(sc, FXP_CSR_SCB_COMMAND, FXP_SCB_COMMAND_CU_START); - ifp->if_timer = 5; + ifp->if_timer = 2; return; } -- cgit v1.1