Fix pass3 Tx DMA - when an mbuf spans a page boundary, make sure that
it either is sitting in contiguous physical RAM or split the mbuf into two Tx descriptors. Not the prettiest patch, but works well in practice - gets about an 8% decrease on CPU time for a simple ttcp TCP Tx benchmark. Thanks to Chris Demetriou for some debugging help. Add some event counters. Remove some #if 0'd debug code.
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simonb
parent
934c6a9eb2
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0c55ae72f4
@ -1,4 +1,4 @@
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/* $NetBSD: sbmac.c,v 1.14 2004/03/14 10:55:45 simonb Exp $ */
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/* $NetBSD: sbmac.c,v 1.15 2004/03/18 05:57:58 simonb Exp $ */
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/*
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* Copyright 2000, 2001
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@ -33,7 +33,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: sbmac.c,v 1.14 2004/03/14 10:55:45 simonb Exp $");
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__KERNEL_RCSID(0, "$NetBSD: sbmac.c,v 1.15 2004/03/18 05:57:58 simonb Exp $");
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#include "bpfilter.h"
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#include "opt_inet.h"
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@ -83,7 +83,6 @@ __KERNEL_RCSID(0, "$NetBSD: sbmac.c,v 1.14 2004/03/14 10:55:45 simonb Exp $");
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#include <mips/sibyte/include/sb1250_dma.h>
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#include <mips/sibyte/include/sb1250_scd.h>
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/* Simple types */
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typedef u_long sbmac_port_t;
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@ -105,6 +104,8 @@ typedef enum { sbmac_state_uninit, sbmac_state_off, sbmac_state_on,
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/* Macros */
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#define SBMAC_EVENT_COUNTERS /* Include counters for various events */
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#define SBDMA_NEXTBUF(d, f) ((((d)->f+1) == (d)->sbdma_dscrtable_end) ? \
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(d)->sbdma_dscrtable : (d)->f+1)
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@ -213,9 +214,25 @@ struct sbmac_softc {
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sbmacdma_t sbm_rxdma;
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int sbm_pass3_dma; /* chip has pass3 SOC DMA features */
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#ifdef SBMAC_EVENT_COUNTERS
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struct evcnt sbm_ev_rxintr; /* Rx interrupts */
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struct evcnt sbm_ev_txintr; /* Tx interrupts */
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struct evcnt sbm_ev_txdrop; /* Tx dropped due to no mbuf alloc failed */
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struct evcnt sbm_ev_txstall; /* Tx stalled due to no descriptors free */
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struct evcnt sbm_ev_txsplit; /* pass3 Tx split mbuf */
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struct evcnt sbm_ev_txkeep; /* pass3 Tx didn't split mbuf */
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#endif
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};
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#ifdef SBMAC_EVENT_COUNTERS
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#define SBMAC_EVCNT_INCR(ev) (ev).ev_count++
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#else
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#define SBMAC_EVCNT_INCR(ev) do { /* nothing */ } while (0)
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#endif
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/* Externs */
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extern paddr_t kvtophys(vaddr_t);
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@ -593,22 +610,10 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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* the ring, the ring is full
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*/
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if (nextdsc == d->sbdma_remptr)
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if (nextdsc == d->sbdma_remptr) {
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SBMAC_EVCNT_INCR(sc->sbm_ev_txstall);
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return ENOSPC;
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#if 0
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do {
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struct mbuf *m0;
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printf("mbuf chain: ");
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for (m0 = m; m0 != 0; m0 = m0->m_next) {
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printf("%d%c/%X ", m0->m_len,
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m0->m_flags & M_EXT ? 'X' : 'N',
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mtod(m0, u_int));
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}
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printf("\n");
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} while (0);
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#endif
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}
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/*
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* PASS3 parts do not have buffer alignment restriction.
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@ -632,7 +637,8 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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*/
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dsc->dscr_b =
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V_DMA_DSCRB_OPTIONS(K_DMA_ETHTX_APPENDCRC_APPENDPAD) |
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V_DMA_DSCRB_A_SIZE((m->m_len + (mtod(m,unsigned int) & 0x0000001F))) |
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V_DMA_DSCRB_A_SIZE((m->m_len +
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(mtod(m,unsigned int) & 0x0000001F))) |
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V_DMA_DSCRB_PKT_SIZE_MSB( (m->m_pkthdr.len & 0xB000) ) |
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V_DMA_DSCRB_PKT_SIZE(m->m_pkthdr.len);
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@ -643,24 +649,50 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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/* Start with first non-head mbuf */
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for(m_temp = m->m_next; m_temp != 0; m_temp = m_temp->m_next) {
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int len, next_len;
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uint64_t addr;
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if (m_temp->m_len == 0)
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continue; /* Skip 0-length mbufs */
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len = m_temp->m_len;
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addr = KVTOPHYS(mtod(m_temp, caddr_t));
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/*
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* Check to see if the mbuf spans a page boundary. If
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* it does, and the physical pages behind the virtual
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* pages are not contiguous, split it so that each
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* virtual page uses it's own Tx descriptor.
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*/
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if (trunc_page(addr) != trunc_page(addr + len - 1)) {
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next_len = (addr + len) - trunc_page(addr + len);
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len -= next_len;
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if (addr + len ==
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KVTOPHYS(mtod(m_temp, caddr_t) + len)) {
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SBMAC_EVCNT_INCR(sc->sbm_ev_txkeep);
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len += next_len;
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next_len = 0;
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} else {
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SBMAC_EVCNT_INCR(sc->sbm_ev_txsplit);
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}
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} else {
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next_len = 0;
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}
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again:
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/*
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* fill in the descriptor
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*/
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dsc->dscr_a = KVTOPHYS(mtod(m_temp,caddr_t)) |
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M_DMA_DSCRA_INTERRUPT;
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dsc->dscr_a = addr | M_DMA_DSCRA_INTERRUPT;
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/*
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* transmitting: set outbound options,buffer A
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* size(+ low 5 bits of start addr)
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*/
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dsc->dscr_b = V_DMA_DSCRB_OPTIONS(K_DMA_ETHTX_NOTSOP) |
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V_DMA_DSCRB_A_SIZE( (m_temp->m_len +
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(mtod(m_temp,unsigned int) & 0x0000001F)) );
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V_DMA_DSCRB_A_SIZE((len + (addr & 0x0000001F)));
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d->sbdma_ctxtable[dsc-d->sbdma_dscrtable] = NULL;
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@ -670,6 +702,7 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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nextdsc = SBDMA_NEXTBUF(d,sbdma_addptr);
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if (nextdsc == d->sbdma_remptr) {
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d->sbdma_addptr = origdesc;
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SBMAC_EVCNT_INCR(sc->sbm_ev_txstall);
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return ENOSPC;
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}
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d->sbdma_addptr = nextdsc;
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@ -677,8 +710,16 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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prevdsc = dsc;
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dsc = d->sbdma_addptr;
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num_mbufs++;
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}
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if (next_len != 0) {
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addr = KVTOPHYS(mtod(m_temp, caddr_t) + len);
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len = next_len;
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next_len = 0;
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goto again;
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}
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}
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/*Set head mbuf to last context index*/
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d->sbdma_ctxtable[prevdsc-d->sbdma_dscrtable] = m;
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} else {
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@ -694,6 +735,7 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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if (m_new == NULL) {
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printf("%s: mbuf allocation failed\n",
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d->sbdma_eth->sc_dev.dv_xname);
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SBMAC_EVCNT_INCR(sc->sbm_ev_txdrop);
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return ENOBUFS;
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}
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@ -702,6 +744,7 @@ sbdma_add_txbuffer(sbmacdma_t *d, struct mbuf *m)
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printf("%s: mbuf cluster allocation failed\n",
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d->sbdma_eth->sc_dev.dv_xname);
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m_freem(m_new);
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SBMAC_EVCNT_INCR(sc->sbm_ev_txdrop);
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return ENOBUFS;
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}
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@ -1077,12 +1120,22 @@ sbmac_initctx(struct sbmac_softc *s)
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SYS_SOC_TYPE(sysrev) == K_SYS_SOC_TYPE_BCM1125H ||
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(SYS_SOC_TYPE(sysrev) == K_SYS_SOC_TYPE_BCM1250 &&
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0));
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#ifdef SBMAC_EVENT_COUNTERS
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evcnt_attach_dynamic(&s->sbm_ev_rxintr, EVCNT_TYPE_INTR,
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NULL, s->sc_dev.dv_xname, "rxintr");
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evcnt_attach_dynamic(&s->sbm_ev_txintr, EVCNT_TYPE_INTR,
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NULL, s->sc_dev.dv_xname, "txintr");
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evcnt_attach_dynamic(&s->sbm_ev_txdrop, EVCNT_TYPE_MISC,
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NULL, s->sc_dev.dv_xname, "txdrop");
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evcnt_attach_dynamic(&s->sbm_ev_txstall, EVCNT_TYPE_MISC,
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NULL, s->sc_dev.dv_xname, "txstall");
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if (s->sbm_pass3_dma) {
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printf("\n");
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printf("%s: disabling unaligned tx DMA\n", s->sc_dev.dv_xname);
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printf("%s", s->sc_dev.dv_xname);
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s->sbm_pass3_dma = 0;
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evcnt_attach_dynamic(&s->sbm_ev_txsplit, EVCNT_TYPE_MISC,
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NULL, s->sc_dev.dv_xname, "pass3tx-split");
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evcnt_attach_dynamic(&s->sbm_ev_txkeep, EVCNT_TYPE_MISC,
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NULL, s->sc_dev.dv_xname, "pass3tx-keep");
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}
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#endif
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}
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/*
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@ -1706,15 +1759,19 @@ sbmac_intr(void *xsc, uint32_t status, uint32_t pc)
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* Transmits on channel 0
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*/
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if (isr & (M_MAC_INT_CHANNEL << S_MAC_TX_CH0))
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if (isr & (M_MAC_INT_CHANNEL << S_MAC_TX_CH0)) {
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sbdma_tx_process(sc, &(sc->sbm_txdma));
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SBMAC_EVCNT_INCR(sc->sbm_ev_txintr);
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}
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/*
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* Receives on channel 0
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*/
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if (isr & (M_MAC_INT_CHANNEL << S_MAC_RX_CH0))
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if (isr & (M_MAC_INT_CHANNEL << S_MAC_RX_CH0)) {
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sbdma_rx_process(sc, &(sc->sbm_rxdma));
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SBMAC_EVCNT_INCR(sc->sbm_ev_rxintr);
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}
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}
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/* try to get more packets going */
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