Refreshed patch against HEAD appears below,
best,
Richard.
PS. Apologies for the quoted-printable encoding...looking now for an email
client capable of 7-bit...
On 10/11/2015, at 5:18 PM, Richard Procter wrote:
> This reduces tsec(4) TX interrupts by over a factor of four per interface,
> boosting throughput by a couple of percent for
>
> $ dd if=/dev/zero bs=4096 | nc ${host} ${port}
>
> It does this by reducing TX interrupts notifications to one per frame, from
> one per mbuf fragment, and by enabling TX interrupt coalescing.
>
> I've chosen conservative coalescing parameters. The card now interrupts every
> four tx frames, leaving the tx ring fuller on average. But ample room remains
> on the card's tx ring of 256 descriptors, which can hold 16 frames in the
> worst case of 16 mbuf fragments per frame. Testing showed descriptor use
> peaking at 13 descriptors under load.
>
> The hold-off timer, ensuring stale frames are not left on the tx ring
> indefinitely, is not crucial for tx: as the frame has already been
> transmitted,
> latency isn't a concern. It need only last longer than the time to transmit
> the
> coalesced frames, and I've set it much longer, roughly 2ms for 1000baseT,
> to give the stack some slack when feeding the card.
>
> While here, also makes tsec_encap() error handling a tad more robust.
>
> Tested on RB600A.
Index: arch/socppc/dev/if_tsec.c
===================================================================
RCS file: /cvs/src/sys/arch/socppc/dev/if_tsec.c,v
retrieving revision 1.42
diff -u -p -U6 -r1.42 if_tsec.c
--- arch/socppc/dev/if_tsec.c 25 Nov 2015 03:09:58 -0000 1.42
+++ arch/socppc/dev/if_tsec.c 3 Dec 2015 20:54:39 -0000
@@ -117,12 +117,14 @@ extern void myetheraddr(u_char *);
#define TSEC_DMACTRL_WOP 0x00000001
#define TSEC_TBIPA 0x030
#define TSEC_TCTRL 0x100
#define TSEC_TSTAT 0x104
#define TSEC_TSTAT_THLT 0x80000000
+#define TSEC_TXIC 0x110
+#define TSEC_TXIC_ICEN 0x80000000
#define TSEC_TBPTR 0x184
#define TSEC_TBASE 0x204
#define TSEC_RCTRL 0x300
#define TSEC_RCTRL_PROM 0x00000008
#define TSEC_RSTAT 0x304
@@ -533,13 +535,13 @@ tsec_start(struct ifnet *ifp)
error = tsec_encap(sc, m, &idx);
if (error == ENOBUFS) {
ifq_deq_rollback(&ifp->if_snd, m);
ifq_set_oactive(&ifp->if_snd);
break;
}
- if (error == EFBIG) {
+ if (error) {
ifq_deq_commit(&ifp->if_snd, m);
m_freem(m); /* give up: drop it */
ifp->if_oerrors++;
continue;
}
@@ -1017,12 +1019,15 @@ tsec_up(struct tsec_softc *sc)
attr = tsec_read(sc, TSEC_ATTR);
attr |= TSEC_ATTR_RDSEN;
attr |= TSEC_ATTR_RBDSEN;
tsec_write(sc, TSEC_ATTR, attr);
+ /* TX interrupts every 4 TSEC_TX_I with ~2ms hold-off @ 1000baseT */
+ tsec_write(sc, TSEC_TXIC, (TSEC_TXIC_ICEN | (0x4 << 21) | 0x1000));
+
tsec_write(sc, TSEC_TSTAT, TSEC_TSTAT_THLT);
tsec_write(sc, TSEC_RSTAT, TSEC_RSTAT_QHLT);
/* Configure media. */
if (LIST_FIRST(&sc->sc_mii.mii_phys))
mii_mediachg(&sc->sc_mii);
@@ -1156,18 +1161,20 @@ tsec_encap(struct tsec_softc *sc, struct
BUS_DMASYNC_PREWRITE);
txd = &sc->sc_txdesc[frag];
for (i = 0; i < map->dm_nsegs; i++) {
status = txd->td_status & TSEC_TX_W;
status |= TSEC_TX_TO1;
+ status |= TSEC_TX_TC;
if (i == (map->dm_nsegs - 1))
- status |= TSEC_TX_L;
+ status |= TSEC_TX_L | TSEC_TX_I;
+
txd->td_len = map->dm_segs[i].ds_len;
txd->td_addr = map->dm_segs[i].ds_addr;
__asm volatile("eieio" ::: "memory");
- txd->td_status = status | TSEC_TX_R | TSEC_TX_I | TSEC_TX_TC;
+ txd->td_status = status | TSEC_TX_R;
bus_dmamap_sync(sc->sc_dmat, TSEC_DMA_MAP(sc->sc_txring),
frag * sizeof(*txd), sizeof(*txd), BUS_DMASYNC_PREWRITE);
cur = frag;
if (status & TSEC_TX_W) {
