From db74a3335e0f645e3139c80bcfc90feb01d8e304 Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo Date: Thu, 15 Sep 2016 19:11:53 -0300 Subject: [PATCH] openvswitch: use percpu flow stats Instead of using flow stats per NUMA node, use it per CPU. When using megaflows, the stats lock can be a bottleneck in scalability. On a E5-2690 12-core system, usual throughput went from ~4Mpps to ~15Mpps when forwarding between two 40GbE ports with a single flow configured on the datapath. This has been tested on a system with possible CPUs 0-7,16-23. After module removal, there were no corruption on the slab cache. Signed-off-by: Thadeu Lima de Souza Cascardo Cc: pravin shelar Acked-by: Pravin B Shelar Signed-off-by: David S. Miller --- net/openvswitch/flow.c | 42 ++++++++++++++++++++++-------------------- net/openvswitch/flow.h | 4 ++-- net/openvswitch/flow_table.c | 26 +++++++++----------------- 3 files changed, 33 insertions(+), 39 deletions(-) diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c index 5b80612..0fa45439 100644 --- a/net/openvswitch/flow.c +++ b/net/openvswitch/flow.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -72,32 +73,33 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags, { struct flow_stats *stats; int node = numa_node_id(); + int cpu = smp_processor_id(); int len = skb->len + (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0); - stats = rcu_dereference(flow->stats[node]); + stats = rcu_dereference(flow->stats[cpu]); - /* Check if already have node-specific stats. */ + /* Check if already have CPU-specific stats. */ if (likely(stats)) { spin_lock(&stats->lock); /* Mark if we write on the pre-allocated stats. */ - if (node == 0 && unlikely(flow->stats_last_writer != node)) - flow->stats_last_writer = node; + if (cpu == 0 && unlikely(flow->stats_last_writer != cpu)) + flow->stats_last_writer = cpu; } else { stats = rcu_dereference(flow->stats[0]); /* Pre-allocated. */ spin_lock(&stats->lock); - /* If the current NUMA-node is the only writer on the + /* If the current CPU is the only writer on the * pre-allocated stats keep using them. */ - if (unlikely(flow->stats_last_writer != node)) { + if (unlikely(flow->stats_last_writer != cpu)) { /* A previous locker may have already allocated the - * stats, so we need to check again. If node-specific + * stats, so we need to check again. If CPU-specific * stats were already allocated, we update the pre- * allocated stats as we have already locked them. */ - if (likely(flow->stats_last_writer != NUMA_NO_NODE) - && likely(!rcu_access_pointer(flow->stats[node]))) { - /* Try to allocate node-specific stats. */ + if (likely(flow->stats_last_writer != -1) && + likely(!rcu_access_pointer(flow->stats[cpu]))) { + /* Try to allocate CPU-specific stats. */ struct flow_stats *new_stats; new_stats = @@ -114,12 +116,12 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags, new_stats->tcp_flags = tcp_flags; spin_lock_init(&new_stats->lock); - rcu_assign_pointer(flow->stats[node], + rcu_assign_pointer(flow->stats[cpu], new_stats); goto unlock; } } - flow->stats_last_writer = node; + flow->stats_last_writer = cpu; } } @@ -136,15 +138,15 @@ void ovs_flow_stats_get(const struct sw_flow *flow, struct ovs_flow_stats *ovs_stats, unsigned long *used, __be16 *tcp_flags) { - int node; + int cpu; *used = 0; *tcp_flags = 0; memset(ovs_stats, 0, sizeof(*ovs_stats)); - /* We open code this to make sure node 0 is always considered */ - for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map)) { - struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]); + /* We open code this to make sure cpu 0 is always considered */ + for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask)) { + struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[cpu]); if (stats) { /* Local CPU may write on non-local stats, so we must @@ -164,11 +166,11 @@ void ovs_flow_stats_get(const struct sw_flow *flow, /* Called with ovs_mutex. */ void ovs_flow_stats_clear(struct sw_flow *flow) { - int node; + int cpu; - /* We open code this to make sure node 0 is always considered */ - for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map)) { - struct flow_stats *stats = ovsl_dereference(flow->stats[node]); + /* We open code this to make sure cpu 0 is always considered */ + for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask)) { + struct flow_stats *stats = ovsl_dereference(flow->stats[cpu]); if (stats) { spin_lock_bh(&stats->lock); diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h index 156a302..ae783f5 100644 --- a/net/openvswitch/flow.h +++ b/net/openvswitch/flow.h @@ -178,14 +178,14 @@ struct sw_flow { struct hlist_node node[2]; u32 hash; } flow_table, ufid_table; - int stats_last_writer; /* NUMA-node id of the last writer on + int stats_last_writer; /* CPU id of the last writer on * 'stats[0]'. */ struct sw_flow_key key; struct sw_flow_id id; struct sw_flow_mask *mask; struct sw_flow_actions __rcu *sf_acts; - struct flow_stats __rcu *stats[]; /* One for each NUMA node. First one + struct flow_stats __rcu *stats[]; /* One for each CPU. First one * is allocated at flow creation time, * the rest are allocated on demand * while holding the 'stats[0].lock'. diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c index 957a3c3..ea7a807 100644 --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -79,17 +80,12 @@ struct sw_flow *ovs_flow_alloc(void) { struct sw_flow *flow; struct flow_stats *stats; - int node; - flow = kmem_cache_alloc(flow_cache, GFP_KERNEL); + flow = kmem_cache_zalloc(flow_cache, GFP_KERNEL); if (!flow) return ERR_PTR(-ENOMEM); - flow->sf_acts = NULL; - flow->mask = NULL; - flow->id.unmasked_key = NULL; - flow->id.ufid_len = 0; - flow->stats_last_writer = NUMA_NO_NODE; + flow->stats_last_writer = -1; /* Initialize the default stat node. */ stats = kmem_cache_alloc_node(flow_stats_cache, @@ -102,10 +98,6 @@ struct sw_flow *ovs_flow_alloc(void) RCU_INIT_POINTER(flow->stats[0], stats); - for_each_node(node) - if (node != 0) - RCU_INIT_POINTER(flow->stats[node], NULL); - return flow; err: kmem_cache_free(flow_cache, flow); @@ -142,17 +134,17 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets) static void flow_free(struct sw_flow *flow) { - int node; + int cpu; if (ovs_identifier_is_key(&flow->id)) kfree(flow->id.unmasked_key); if (flow->sf_acts) ovs_nla_free_flow_actions((struct sw_flow_actions __force *)flow->sf_acts); - /* We open code this to make sure node 0 is always considered */ - for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map)) - if (node != 0 && flow->stats[node]) + /* We open code this to make sure cpu 0 is always considered */ + for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask)) + if (flow->stats[cpu]) kmem_cache_free(flow_stats_cache, - (struct flow_stats __force *)flow->stats[node]); + (struct flow_stats __force *)flow->stats[cpu]); kmem_cache_free(flow_cache, flow); } @@ -757,7 +749,7 @@ int ovs_flow_init(void) BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long)); flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow) - + (nr_node_ids + + (nr_cpu_ids * sizeof(struct flow_stats *)), 0, 0, NULL); if (flow_cache == NULL) -- 2.7.4