Message ID | 1479375798-10968-1-git-send-email-cascardo@redhat.com |
---|---|
State | Accepted |
Delegated to: | Daniele Di Proietto |
Headers | show |
On 17/11/2016 01:43, "Thadeu Lima de Souza Cascardo" <cascardo@redhat.com> wrote: >From: Ilya Maximets <i.maximets@samsung.com> > >Current implementarion of TX packet's queueing is broken in several ways: > > * TX queue flushing implemented on receive assumes that all > core_id-s are sequential and starts from zero. This may lead > to situation when packets will stuck in queue forever and, > also, this influences on latency. > > * For a long time flushing logic depends on uninitialized > 'txq_needs_locking', because it usually calculated after > 'netdev_dpdk_alloc_txq' but used inside of this function > for initialization of 'flush_tx'. > >Testing shows no performance difference with and without queueing. >Lets remove queueing at all because it doesn't work properly now and >also does not increase performance. > >This improves latency compared to current openvswitch 2.5. > >Without the patch: > >Device 0->1: > Throughput: 6.8683 Mpps > Min. Latency: 39.9780 usec > Avg. Latency: 61.1226 usec > Max. Latency: 89.1110 usec > >Device 1->0: > Throughput: 6.8683 Mpps > Min. Latency: 41.0660 usec > Avg. Latency: 58.7778 usec > Max. Latency: 89.4720 usec > >With the patch: > >Device 0->1: > Throughput: 6.3941 Mpps > Min. Latency: 10.5410 usec > Avg. Latency: 14.1309 usec > Max. Latency: 28.9880 usec > >Device 1->0: > Throughput: 6.3941 Mpps > Min. Latency: 11.9780 usec > Avg. Latency: 18.0692 usec > Max. Latency: 29.5200 > >Signed-off-by: Ilya Maximets <i.maximets@samsung.com> >Acked-by: Daniele Di Proietto <diproiettod@vmware.com> >Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com> Applied to branch-2.5, thanks >--- > lib/netdev-dpdk.c | 104 ++++++++---------------------------------------------- > 1 file changed, 14 insertions(+), 90 deletions(-) > >diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c >index 6e68c07..58d2f8e 100644 >--- a/lib/netdev-dpdk.c >+++ b/lib/netdev-dpdk.c >@@ -131,7 +131,6 @@ static const struct rte_eth_conf port_conf = { > }, > }; > >-enum { MAX_TX_QUEUE_LEN = 384 }; > enum { DPDK_RING_SIZE = 256 }; > BUILD_ASSERT_DECL(IS_POW2(DPDK_RING_SIZE)); > enum { DRAIN_TSC = 200000ULL }; >@@ -153,8 +152,7 @@ static struct ovs_list dpdk_mp_list OVS_GUARDED_BY(dpdk_mutex) > = OVS_LIST_INITIALIZER(&dpdk_mp_list); > > /* This mutex must be used by non pmd threads when allocating or freeing >- * mbufs through mempools. Since dpdk_queue_pkts() and dpdk_queue_flush() may >- * use mempools, a non pmd thread should hold this mutex while calling them */ >+ * mbufs through mempools. */ > static struct ovs_mutex nonpmd_mempool_mutex = OVS_MUTEX_INITIALIZER; > > struct dpdk_mp { >@@ -168,17 +166,12 @@ struct dpdk_mp { > /* There should be one 'struct dpdk_tx_queue' created for > * each cpu core. */ > struct dpdk_tx_queue { >- bool flush_tx; /* Set to true to flush queue everytime */ >- /* pkts are queued. */ >- int count; > rte_spinlock_t tx_lock; /* Protects the members and the NIC queue > * from concurrent access. It is used only > * if the queue is shared among different > * pmd threads (see 'txq_needs_locking'). */ > int map; /* Mapping of configured vhost-user queues > * to enabled by guest. */ >- uint64_t tsc; >- struct rte_mbuf *burst_pkts[MAX_TX_QUEUE_LEN]; > }; > > /* dpdk has no way to remove dpdk ring ethernet devices >@@ -566,19 +559,6 @@ netdev_dpdk_alloc_txq(struct netdev_dpdk *netdev, unsigned int n_txqs) > > netdev->tx_q = dpdk_rte_mzalloc(n_txqs * sizeof *netdev->tx_q); > for (i = 0; i < n_txqs; i++) { >- int numa_id = ovs_numa_get_numa_id(i); >- >- if (!netdev->txq_needs_locking) { >- /* Each index is considered as a cpu core id, since there should >- * be one tx queue for each cpu core. If the corresponding core >- * is not on the same numa node as 'netdev', flags the >- * 'flush_tx'. */ >- netdev->tx_q[i].flush_tx = netdev->socket_id == numa_id; >- } else { >- /* Queues are shared among CPUs. Always flush */ >- netdev->tx_q[i].flush_tx = true; >- } >- > /* Initialize map for vhost devices. */ > netdev->tx_q[i].map = OVS_VHOST_QUEUE_MAP_UNKNOWN; > rte_spinlock_init(&netdev->tx_q[i].tx_lock); >@@ -952,16 +932,15 @@ netdev_dpdk_rxq_dealloc(struct netdev_rxq *rxq_) > } > > static inline void >-dpdk_queue_flush__(struct netdev_dpdk *dev, int qid) >+netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int qid, >+ struct rte_mbuf **pkts, int cnt) > { >- struct dpdk_tx_queue *txq = &dev->tx_q[qid]; > uint32_t nb_tx = 0; > >- while (nb_tx != txq->count) { >+ while (nb_tx != cnt) { > uint32_t ret; > >- ret = rte_eth_tx_burst(dev->port_id, qid, txq->burst_pkts + nb_tx, >- txq->count - nb_tx); >+ ret = rte_eth_tx_burst(dev->port_id, qid, pkts + nb_tx, cnt - nb_tx); > if (!ret) { > break; > } >@@ -969,32 +948,18 @@ dpdk_queue_flush__(struct netdev_dpdk *dev, int qid) > nb_tx += ret; > } > >- if (OVS_UNLIKELY(nb_tx != txq->count)) { >+ if (OVS_UNLIKELY(nb_tx != cnt)) { > /* free buffers, which we couldn't transmit, one at a time (each > * packet could come from a different mempool) */ > int i; > >- for (i = nb_tx; i < txq->count; i++) { >- rte_pktmbuf_free(txq->burst_pkts[i]); >+ for (i = nb_tx; i < cnt; i++) { >+ rte_pktmbuf_free(pkts[i]); > } > rte_spinlock_lock(&dev->stats_lock); >- dev->stats.tx_dropped += txq->count-nb_tx; >+ dev->stats.tx_dropped += cnt - nb_tx; > rte_spinlock_unlock(&dev->stats_lock); > } >- >- txq->count = 0; >- txq->tsc = rte_get_timer_cycles(); >-} >- >-static inline void >-dpdk_queue_flush(struct netdev_dpdk *dev, int qid) >-{ >- struct dpdk_tx_queue *txq = &dev->tx_q[qid]; >- >- if (txq->count == 0) { >- return; >- } >- dpdk_queue_flush__(dev, qid); > } > > static bool >@@ -1076,19 +1041,8 @@ netdev_dpdk_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet **packets, > int *c) > { > struct netdev_rxq_dpdk *rx = netdev_rxq_dpdk_cast(rxq_); >- struct netdev *netdev = rx->up.netdev; >- struct netdev_dpdk *dev = netdev_dpdk_cast(netdev); > int nb_rx; > >- /* There is only one tx queue for this core. Do not flush other >- * queues. >- * Do not flush tx queue which is shared among CPUs >- * since it is always flushed */ >- if (rxq_->queue_id == rte_lcore_id() && >- OVS_LIKELY(!dev->txq_needs_locking)) { >- dpdk_queue_flush(dev, rxq_->queue_id); >- } >- > nb_rx = rte_eth_rx_burst(rx->port_id, rxq_->queue_id, > (struct rte_mbuf **) packets, > NETDEV_MAX_BURST); >@@ -1175,35 +1129,6 @@ out: > } > } > >-inline static void >-dpdk_queue_pkts(struct netdev_dpdk *dev, int qid, >- struct rte_mbuf **pkts, int cnt) >-{ >- struct dpdk_tx_queue *txq = &dev->tx_q[qid]; >- uint64_t diff_tsc; >- >- int i = 0; >- >- while (i < cnt) { >- int freeslots = MAX_TX_QUEUE_LEN - txq->count; >- int tocopy = MIN(freeslots, cnt-i); >- >- memcpy(&txq->burst_pkts[txq->count], &pkts[i], >- tocopy * sizeof (struct rte_mbuf *)); >- >- txq->count += tocopy; >- i += tocopy; >- >- if (txq->count == MAX_TX_QUEUE_LEN || txq->flush_tx) { >- dpdk_queue_flush__(dev, qid); >- } >- diff_tsc = rte_get_timer_cycles() - txq->tsc; >- if (diff_tsc >= DRAIN_TSC) { >- dpdk_queue_flush__(dev, qid); >- } >- } >-} >- > /* Tx function. Transmit packets indefinitely */ > static void > dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts, >@@ -1265,8 +1190,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts, > if (dev->type == DPDK_DEV_VHOST) { > __netdev_dpdk_vhost_send(netdev, qid, (struct dp_packet **) mbufs, newcnt, true); > } else { >- dpdk_queue_pkts(dev, qid, mbufs, newcnt); >- dpdk_queue_flush(dev, qid); >+ netdev_dpdk_eth_tx_burst(dev, qid, mbufs, newcnt); > } > > if (!dpdk_thread_is_pmd()) { >@@ -1324,7 +1248,7 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid, > > if (OVS_UNLIKELY(size > dev->max_packet_len)) { > if (next_tx_idx != i) { >- dpdk_queue_pkts(dev, qid, >+ netdev_dpdk_eth_tx_burst(dev, qid, > (struct rte_mbuf **)&pkts[next_tx_idx], > i-next_tx_idx); > } >@@ -1338,9 +1262,9 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid, > } > } > if (next_tx_idx != cnt) { >- dpdk_queue_pkts(dev, qid, >- (struct rte_mbuf **)&pkts[next_tx_idx], >- cnt-next_tx_idx); >+ netdev_dpdk_eth_tx_burst(dev, qid, >+ (struct rte_mbuf **)&pkts[next_tx_idx], >+ cnt-next_tx_idx); > } > > if (OVS_UNLIKELY(dropped)) { >-- >2.7.4 >
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index 6e68c07..58d2f8e 100644 --- a/lib/netdev-dpdk.c +++ b/lib/netdev-dpdk.c @@ -131,7 +131,6 @@ static const struct rte_eth_conf port_conf = { }, }; -enum { MAX_TX_QUEUE_LEN = 384 }; enum { DPDK_RING_SIZE = 256 }; BUILD_ASSERT_DECL(IS_POW2(DPDK_RING_SIZE)); enum { DRAIN_TSC = 200000ULL }; @@ -153,8 +152,7 @@ static struct ovs_list dpdk_mp_list OVS_GUARDED_BY(dpdk_mutex) = OVS_LIST_INITIALIZER(&dpdk_mp_list); /* This mutex must be used by non pmd threads when allocating or freeing - * mbufs through mempools. Since dpdk_queue_pkts() and dpdk_queue_flush() may - * use mempools, a non pmd thread should hold this mutex while calling them */ + * mbufs through mempools. */ static struct ovs_mutex nonpmd_mempool_mutex = OVS_MUTEX_INITIALIZER; struct dpdk_mp { @@ -168,17 +166,12 @@ struct dpdk_mp { /* There should be one 'struct dpdk_tx_queue' created for * each cpu core. */ struct dpdk_tx_queue { - bool flush_tx; /* Set to true to flush queue everytime */ - /* pkts are queued. */ - int count; rte_spinlock_t tx_lock; /* Protects the members and the NIC queue * from concurrent access. It is used only * if the queue is shared among different * pmd threads (see 'txq_needs_locking'). */ int map; /* Mapping of configured vhost-user queues * to enabled by guest. */ - uint64_t tsc; - struct rte_mbuf *burst_pkts[MAX_TX_QUEUE_LEN]; }; /* dpdk has no way to remove dpdk ring ethernet devices @@ -566,19 +559,6 @@ netdev_dpdk_alloc_txq(struct netdev_dpdk *netdev, unsigned int n_txqs) netdev->tx_q = dpdk_rte_mzalloc(n_txqs * sizeof *netdev->tx_q); for (i = 0; i < n_txqs; i++) { - int numa_id = ovs_numa_get_numa_id(i); - - if (!netdev->txq_needs_locking) { - /* Each index is considered as a cpu core id, since there should - * be one tx queue for each cpu core. If the corresponding core - * is not on the same numa node as 'netdev', flags the - * 'flush_tx'. */ - netdev->tx_q[i].flush_tx = netdev->socket_id == numa_id; - } else { - /* Queues are shared among CPUs. Always flush */ - netdev->tx_q[i].flush_tx = true; - } - /* Initialize map for vhost devices. */ netdev->tx_q[i].map = OVS_VHOST_QUEUE_MAP_UNKNOWN; rte_spinlock_init(&netdev->tx_q[i].tx_lock); @@ -952,16 +932,15 @@ netdev_dpdk_rxq_dealloc(struct netdev_rxq *rxq_) } static inline void -dpdk_queue_flush__(struct netdev_dpdk *dev, int qid) +netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int qid, + struct rte_mbuf **pkts, int cnt) { - struct dpdk_tx_queue *txq = &dev->tx_q[qid]; uint32_t nb_tx = 0; - while (nb_tx != txq->count) { + while (nb_tx != cnt) { uint32_t ret; - ret = rte_eth_tx_burst(dev->port_id, qid, txq->burst_pkts + nb_tx, - txq->count - nb_tx); + ret = rte_eth_tx_burst(dev->port_id, qid, pkts + nb_tx, cnt - nb_tx); if (!ret) { break; } @@ -969,32 +948,18 @@ dpdk_queue_flush__(struct netdev_dpdk *dev, int qid) nb_tx += ret; } - if (OVS_UNLIKELY(nb_tx != txq->count)) { + if (OVS_UNLIKELY(nb_tx != cnt)) { /* free buffers, which we couldn't transmit, one at a time (each * packet could come from a different mempool) */ int i; - for (i = nb_tx; i < txq->count; i++) { - rte_pktmbuf_free(txq->burst_pkts[i]); + for (i = nb_tx; i < cnt; i++) { + rte_pktmbuf_free(pkts[i]); } rte_spinlock_lock(&dev->stats_lock); - dev->stats.tx_dropped += txq->count-nb_tx; + dev->stats.tx_dropped += cnt - nb_tx; rte_spinlock_unlock(&dev->stats_lock); } - - txq->count = 0; - txq->tsc = rte_get_timer_cycles(); -} - -static inline void -dpdk_queue_flush(struct netdev_dpdk *dev, int qid) -{ - struct dpdk_tx_queue *txq = &dev->tx_q[qid]; - - if (txq->count == 0) { - return; - } - dpdk_queue_flush__(dev, qid); } static bool @@ -1076,19 +1041,8 @@ netdev_dpdk_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet **packets, int *c) { struct netdev_rxq_dpdk *rx = netdev_rxq_dpdk_cast(rxq_); - struct netdev *netdev = rx->up.netdev; - struct netdev_dpdk *dev = netdev_dpdk_cast(netdev); int nb_rx; - /* There is only one tx queue for this core. Do not flush other - * queues. - * Do not flush tx queue which is shared among CPUs - * since it is always flushed */ - if (rxq_->queue_id == rte_lcore_id() && - OVS_LIKELY(!dev->txq_needs_locking)) { - dpdk_queue_flush(dev, rxq_->queue_id); - } - nb_rx = rte_eth_rx_burst(rx->port_id, rxq_->queue_id, (struct rte_mbuf **) packets, NETDEV_MAX_BURST); @@ -1175,35 +1129,6 @@ out: } } -inline static void -dpdk_queue_pkts(struct netdev_dpdk *dev, int qid, - struct rte_mbuf **pkts, int cnt) -{ - struct dpdk_tx_queue *txq = &dev->tx_q[qid]; - uint64_t diff_tsc; - - int i = 0; - - while (i < cnt) { - int freeslots = MAX_TX_QUEUE_LEN - txq->count; - int tocopy = MIN(freeslots, cnt-i); - - memcpy(&txq->burst_pkts[txq->count], &pkts[i], - tocopy * sizeof (struct rte_mbuf *)); - - txq->count += tocopy; - i += tocopy; - - if (txq->count == MAX_TX_QUEUE_LEN || txq->flush_tx) { - dpdk_queue_flush__(dev, qid); - } - diff_tsc = rte_get_timer_cycles() - txq->tsc; - if (diff_tsc >= DRAIN_TSC) { - dpdk_queue_flush__(dev, qid); - } - } -} - /* Tx function. Transmit packets indefinitely */ static void dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts, @@ -1265,8 +1190,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts, if (dev->type == DPDK_DEV_VHOST) { __netdev_dpdk_vhost_send(netdev, qid, (struct dp_packet **) mbufs, newcnt, true); } else { - dpdk_queue_pkts(dev, qid, mbufs, newcnt); - dpdk_queue_flush(dev, qid); + netdev_dpdk_eth_tx_burst(dev, qid, mbufs, newcnt); } if (!dpdk_thread_is_pmd()) { @@ -1324,7 +1248,7 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid, if (OVS_UNLIKELY(size > dev->max_packet_len)) { if (next_tx_idx != i) { - dpdk_queue_pkts(dev, qid, + netdev_dpdk_eth_tx_burst(dev, qid, (struct rte_mbuf **)&pkts[next_tx_idx], i-next_tx_idx); } @@ -1338,9 +1262,9 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid, } } if (next_tx_idx != cnt) { - dpdk_queue_pkts(dev, qid, - (struct rte_mbuf **)&pkts[next_tx_idx], - cnt-next_tx_idx); + netdev_dpdk_eth_tx_burst(dev, qid, + (struct rte_mbuf **)&pkts[next_tx_idx], + cnt-next_tx_idx); } if (OVS_UNLIKELY(dropped)) {