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- Avoid lock contention in the if_transmit callback by using trylock and

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enqueueing the frames when it fails. This way there is some latency
 removed from the transmitting path.
- If IFF_DRV_OACTIVE is set (and also if IFF_DRV_RUNNING is not) just
 enqueue the desired frames and return successful transmit. This way we
 avoid to return errors on transmit side and resulting in
 possible out-of-order frames. Please note that IFF_DRV_OACTIVE is set
 everytime we get the threshold ring hit, so this can be happening quite
 often.

Submitted by:	Attilio.Rao@isilon.com
MFC after:5 days
This commit is contained in:
David C Somayajulu 2015-07-28 19:15:44 +00:00
parent 75f66cde5c
commit ab97207add
2 changed files with 15 additions and 22 deletions
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36
sys/dev/bxe/bxe.c
View File

@ -5999,19 +5999,26 @@ bxe_tx_mq_start_locked(struct bxe_softc *sc,
rc = tx_count = 0;
BXE_FP_TX_LOCK_ASSERT(fp);
if (!tx_br) {
BLOGE(sc, "Multiqueue TX and no buf_ring!\n");
return (EINVAL);
}
if (!sc->link_vars.link_up ||
(ifp->if_drv_flags &
(IFF_DRV_RUNNING | IFF_DRV_OACTIVE)) != IFF_DRV_RUNNING) {
rc = drbr_enqueue_drv(ifp, tx_br, m);
goto bxe_tx_mq_start_locked_exit;
}
/* fetch the depth of the driver queue */
depth = drbr_inuse_drv(ifp, tx_br);
if (depth > fp->eth_q_stats.tx_max_drbr_queue_depth) {
fp->eth_q_stats.tx_max_drbr_queue_depth = depth;
}
BXE_FP_TX_LOCK_ASSERT(fp);
if (m == NULL) {
/* no new work, check for pending frames */
next = drbr_dequeue_drv(ifp, tx_br);
@ -6103,26 +6110,11 @@ bxe_tx_mq_start(struct ifnet *ifp,
fp = &sc->fp[fp_index];
if (!(if_getdrvflags(ifp) & IFF_DRV_RUNNING)) {
BLOGW(sc, "Interface not running, ignoring transmit request\n");
return (ENETDOWN);
}
if (if_getdrvflags(ifp) & IFF_DRV_OACTIVE) {
BLOGW(sc, "Interface TX queue is full, ignoring transmit request\n");
return (EBUSY);
}
if (!sc->link_vars.link_up) {
BLOGW(sc, "Interface link is down, ignoring transmit request\n");
return (ENETDOWN);
}
/* XXX change to TRYLOCK here and if failed then schedule taskqueue */
BXE_FP_TX_LOCK(fp);
rc = bxe_tx_mq_start_locked(sc, ifp, fp, m);
BXE_FP_TX_UNLOCK(fp);
if (BXE_FP_TX_TRYLOCK(fp)) {
rc = bxe_tx_mq_start_locked(sc, ifp, fp, m);
BXE_FP_TX_UNLOCK(fp);
} else
rc = drbr_enqueue_drv(ifp, fp->tx_br, m);
return (rc);
}

1
sys/dev/bxe/bxe.h
View File

@ -582,6 +582,7 @@ struct bxe_fastpath {
#define BXE_FP_TX_LOCK(fp) mtx_lock(&fp->tx_mtx)
#define BXE_FP_TX_UNLOCK(fp) mtx_unlock(&fp->tx_mtx)
#define BXE_FP_TX_LOCK_ASSERT(fp) mtx_assert(&fp->tx_mtx, MA_OWNED)
#define BXE_FP_TX_TRYLOCK(fp) mtx_trylock(&fp->tx_mtx)
#define BXE_FP_RX_LOCK(fp) mtx_lock(&fp->rx_mtx)
#define BXE_FP_RX_UNLOCK(fp) mtx_unlock(&fp->rx_mtx)