Author: davidcs
Date: Tue Jul 28 19:15:44 2015
New Revision: 285973
URL: https://svnweb.freebsd.org/changeset/base/285973
Log:
- Avoid lock contention in the if_transmit callback by using trylock and
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@isilon.com
MFC after:5 days
Modified:
head/sys/dev/bxe/bxe.c
head/sys/dev/bxe/bxe.h
Modified: head/sys/dev/bxe/bxe.c
==
--- head/sys/dev/bxe/bxe.c Tue Jul 28 18:41:28 2015(r285972)
+++ head/sys/dev/bxe/bxe.c Tue Jul 28 19:15:44 2015(r285973)
@@ -5999,19 +5999,26 @@ bxe_tx_mq_start_locked(struct bxe_softc
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);
}
Modified: head/sys/dev/bxe/bxe.h
==
--- head/sys/dev/bxe/bxe.h Tue Jul 28 18:41:28 2015(r285972)
+++ head/sys/dev/bxe/bxe.h Tue Jul 28 19:15:44 2015(r285973)
@@ -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)
___
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