This allows to collect packets from more than one RX burst and send them together with a configurable maximum latency.
'other_config:output-max-latency' can be used to configure time that a packet can wait in output batch for sending. Signed-off-by: Ilya Maximets <i.maxim...@samsung.com> --- millisecon granularity is used for now. Can be easily switched to use microseconds instead. lib/dpif-netdev.c | 97 +++++++++++++++++++++++++++++++++++++++++++--------- vswitchd/vswitch.xml | 15 ++++++++ 2 files changed, 95 insertions(+), 17 deletions(-) diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 07c7dad..e5f8a3d 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -84,6 +84,9 @@ VLOG_DEFINE_THIS_MODULE(dpif_netdev); #define MAX_RECIRC_DEPTH 5 DEFINE_STATIC_PER_THREAD_DATA(uint32_t, recirc_depth, 0) +/* Use instant packet send by default. */ +#define DEFAULT_OUTPUT_MAX_LATENCY 0 + /* Configuration parameters. */ enum { MAX_FLOWS = 65536 }; /* Maximum number of flows in flow table. */ enum { MAX_METERS = 65536 }; /* Maximum number of meters. */ @@ -261,6 +264,9 @@ struct dp_netdev { struct hmap ports; struct seq *port_seq; /* Incremented whenever a port changes. */ + /* The time that a packet can wait in output batch for sending. */ + atomic_uint32_t output_max_latency; + /* Meters. */ struct ovs_mutex meter_locks[N_METER_LOCKS]; struct dp_meter *meters[MAX_METERS]; /* Meter bands. */ @@ -498,6 +504,7 @@ struct tx_port { int qid; long long last_used; struct hmap_node node; + long long output_time; struct dp_packet_batch output_pkts; }; @@ -570,6 +577,9 @@ struct dp_netdev_pmd_thread { * than 'cmap_count(dp->poll_threads)'. */ const int static_tx_qid; + /* Number of filled output batches. */ + int n_output_batches; + struct ovs_mutex port_mutex; /* Mutex for 'poll_list' and 'tx_ports'. */ /* List of rx queues to poll. */ struct hmap poll_list OVS_GUARDED; @@ -663,9 +673,9 @@ static void dp_netdev_add_rxq_to_pmd(struct dp_netdev_pmd_thread *pmd, static void dp_netdev_del_rxq_from_pmd(struct dp_netdev_pmd_thread *pmd, struct rxq_poll *poll) OVS_REQUIRES(pmd->port_mutex); -static void +static int dp_netdev_pmd_flush_output_packets(struct dp_netdev_pmd_thread *pmd, - long long now); + long long now, bool force); static void reconfigure_datapath(struct dp_netdev *dp) OVS_REQUIRES(dp->port_mutex); static bool dp_netdev_pmd_try_ref(struct dp_netdev_pmd_thread *pmd); @@ -1188,6 +1198,7 @@ create_dp_netdev(const char *name, const struct dpif_class *class, conntrack_init(&dp->conntrack); atomic_init(&dp->emc_insert_min, DEFAULT_EM_FLOW_INSERT_MIN); + atomic_init(&dp->output_max_latency, DEFAULT_OUTPUT_MAX_LATENCY); cmap_init(&dp->poll_threads); ovs_mutex_init_recursive(&dp->non_pmd_mutex); @@ -2843,7 +2854,7 @@ dpif_netdev_execute(struct dpif *dpif, struct dpif_execute *execute) dp_packet_batch_init_packet(&pp, execute->packet); dp_netdev_execute_actions(pmd, &pp, false, execute->flow, execute->actions, execute->actions_len, now); - dp_netdev_pmd_flush_output_packets(pmd, now); + dp_netdev_pmd_flush_output_packets(pmd, now, true); if (pmd->core_id == NON_PMD_CORE_ID) { ovs_mutex_unlock(&dp->non_pmd_mutex); @@ -2892,6 +2903,16 @@ dpif_netdev_set_config(struct dpif *dpif, const struct smap *other_config) smap_get_ullong(other_config, "emc-insert-inv-prob", DEFAULT_EM_FLOW_INSERT_INV_PROB); uint32_t insert_min, cur_min; + uint32_t output_max_latency, cur_max_latency; + + output_max_latency = smap_get_int(other_config, "output-max-latency", + DEFAULT_OUTPUT_MAX_LATENCY); + atomic_read_relaxed(&dp->output_max_latency, &cur_max_latency); + if (output_max_latency != cur_max_latency) { + atomic_store_relaxed(&dp->output_max_latency, output_max_latency); + VLOG_INFO("Output maximum latency set to %"PRIu32" ms", + output_max_latency); + } if (!nullable_string_is_equal(dp->pmd_cmask, cmask)) { free(dp->pmd_cmask); @@ -3092,11 +3113,12 @@ cycles_count_intermediate(struct dp_netdev_pmd_thread *pmd, non_atomic_ullong_add(&pmd->cycles.n[type], interval); } -static void +static int dp_netdev_pmd_flush_output_on_port(struct dp_netdev_pmd_thread *pmd, struct tx_port *p, long long now) { int tx_qid; + int output_cnt; bool dynamic_txqs; dynamic_txqs = p->port->dynamic_txqs; @@ -3106,21 +3128,39 @@ dp_netdev_pmd_flush_output_on_port(struct dp_netdev_pmd_thread *pmd, tx_qid = pmd->static_tx_qid; } + output_cnt = dp_packet_batch_size(&p->output_pkts); netdev_send(p->port->netdev, tx_qid, &p->output_pkts, dynamic_txqs); dp_packet_batch_init(&p->output_pkts); + + if (output_cnt) { + ovs_assert(pmd->n_output_batches > 0); + pmd->n_output_batches--; + } + return output_cnt; } -static void +static int dp_netdev_pmd_flush_output_packets(struct dp_netdev_pmd_thread *pmd, - long long now) + long long now, bool force) { struct tx_port *p; + int output_cnt = 0; + + if (!pmd->n_output_batches) { + return 0; + } + + if (!now) { + now = time_msec(); + } HMAP_FOR_EACH (p, node, &pmd->send_port_cache) { - if (!dp_packet_batch_is_empty(&p->output_pkts)) { - dp_netdev_pmd_flush_output_on_port(pmd, p, now); + if (!dp_packet_batch_is_empty(&p->output_pkts) + && (force || p->output_time <= now)) { + output_cnt += dp_netdev_pmd_flush_output_on_port(pmd, p, now); } } + return output_cnt; } static int @@ -3130,7 +3170,7 @@ dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd, { struct dp_packet_batch batch; int error; - int batch_cnt = 0; + int batch_cnt = 0, output_cnt = 0; dp_packet_batch_init(&batch); error = netdev_rxq_recv(rx, &batch); @@ -3141,7 +3181,7 @@ dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd, batch_cnt = batch.count; dp_netdev_input(pmd, &batch, port_no, now); - dp_netdev_pmd_flush_output_packets(pmd, now); + output_cnt = dp_netdev_pmd_flush_output_packets(pmd, now, false); } else if (error != EAGAIN && error != EOPNOTSUPP) { static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); @@ -3149,7 +3189,7 @@ dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd, netdev_rxq_get_name(rx), ovs_strerror(error)); } - return batch_cnt; + return batch_cnt + output_cnt; } static struct tx_port * @@ -3685,6 +3725,8 @@ pmd_free_cached_ports(struct dp_netdev_pmd_thread *pmd) { struct tx_port *tx_port_cached; + /* Flush all the queued packets. */ + dp_netdev_pmd_flush_output_packets(pmd, 0, true); /* Free all used tx queue ids. */ dpif_netdev_xps_revalidate_pmd(pmd, 0, true); @@ -3759,7 +3801,6 @@ pmd_thread_main(void *f_) bool exiting; int poll_cnt; int i; - int process_packets = 0; poll_list = NULL; @@ -3788,8 +3829,10 @@ reload: cycles_count_start(pmd); for (;;) { + int process_packets = 0; + for (i = 0; i < poll_cnt; i++) { - process_packets = + process_packets += dp_netdev_process_rxq_port(pmd, poll_list[i].rx, poll_list[i].port_no); cycles_count_intermediate(pmd, @@ -3797,6 +3840,16 @@ reload: : PMD_CYCLES_IDLE); } + if (!process_packets) { + /* We didn't receive anything in the process loop. + * Check if we need to send something. */ + process_packets = dp_netdev_pmd_flush_output_packets(pmd, + 0, false); + cycles_count_intermediate(pmd, + process_packets ? PMD_CYCLES_PROCESSING + : PMD_CYCLES_IDLE); + } + if (lc++ > 1024) { bool reload; @@ -4234,6 +4287,8 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp, pmd->numa_id = numa_id; pmd->need_reload = false; + pmd->n_output_batches = 0; + *CONST_CAST(int *, &pmd->static_tx_qid) = cmap_count(&dp->poll_threads); ovs_refcount_init(&pmd->ref_cnt); @@ -4418,6 +4473,7 @@ dp_netdev_add_port_tx_to_pmd(struct dp_netdev_pmd_thread *pmd, tx->port = port; tx->qid = -1; + tx->output_time = 0LL; dp_packet_batch_init(&tx->output_pkts); hmap_insert(&pmd->tx_ports, &tx->node, hash_port_no(tx->port->port_no)); @@ -5094,11 +5150,18 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_, dp_netdev_pmd_flush_output_on_port(pmd, p, now); } #endif + if (dp_packet_batch_is_empty(&p->output_pkts)) { + uint32_t cur_max_latency; + + atomic_read_relaxed(&dp->output_max_latency, &cur_max_latency); + p->output_time = now + cur_max_latency; - if (OVS_UNLIKELY(dp_packet_batch_size(&p->output_pkts) - + dp_packet_batch_size(packets_) > NETDEV_MAX_BURST)) { - /* Some packets was generated while input batch processing. - * Flush here to avoid overflow. */ + if (dp_packet_batch_size(packets_)) { + pmd->n_output_batches++; + } + } else if (dp_packet_batch_size(&p->output_pkts) + + dp_packet_batch_size(packets_) > NETDEV_MAX_BURST) { + /* Flush here to avoid overflow. */ dp_netdev_pmd_flush_output_on_port(pmd, p, now); } diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index 074535b..23930f0 100644 --- a/vswitchd/vswitch.xml +++ b/vswitchd/vswitch.xml @@ -344,6 +344,21 @@ </p> </column> + <column name="other_config" key="output-max-latency" + type='{"type": "integer", "minInteger": 0, "maxInteger": 1000}'> + <p> + Specifies the time in milliseconds that a packet can wait in output + batch for sending i.e. amount of time that packet can spend in an + intermediate output queue before sending to netdev. + This option can be used to configure balance between throughput + and latency. Lower values decreases latency while higher values + may be useful to achieve higher performance. + </p> + <p> + Defaults to 0 i.e. instant packet sending (latency optimized). + </p> + </column> + <column name="other_config" key="n-handler-threads" type='{"type": "integer", "minInteger": 1}'> <p> -- 2.7.4 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev