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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 <cascardo@redhat.com> Cc: pravin shelar <pshelar@ovn.org> Acked-by: Pravin B Shelar <pshelar@ovn.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -29,6 +29,7 @@
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#include <linux/module.h>
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#include <linux/in.h>
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#include <linux/rcupdate.h>
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#include <linux/cpumask.h>
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#include <linux/if_arp.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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@ -72,32 +73,33 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags,
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{
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struct flow_stats *stats;
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int node = numa_node_id();
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int cpu = smp_processor_id();
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int len = skb->len + (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
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stats = rcu_dereference(flow->stats[node]);
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stats = rcu_dereference(flow->stats[cpu]);
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/* Check if already have node-specific stats. */
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/* Check if already have CPU-specific stats. */
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if (likely(stats)) {
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spin_lock(&stats->lock);
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/* Mark if we write on the pre-allocated stats. */
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if (node == 0 && unlikely(flow->stats_last_writer != node))
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flow->stats_last_writer = node;
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if (cpu == 0 && unlikely(flow->stats_last_writer != cpu))
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flow->stats_last_writer = cpu;
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} else {
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stats = rcu_dereference(flow->stats[0]); /* Pre-allocated. */
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spin_lock(&stats->lock);
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/* If the current NUMA-node is the only writer on the
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/* If the current CPU is the only writer on the
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* pre-allocated stats keep using them.
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*/
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if (unlikely(flow->stats_last_writer != node)) {
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if (unlikely(flow->stats_last_writer != cpu)) {
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/* A previous locker may have already allocated the
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* stats, so we need to check again. If node-specific
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* stats, so we need to check again. If CPU-specific
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* stats were already allocated, we update the pre-
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* allocated stats as we have already locked them.
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*/
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if (likely(flow->stats_last_writer != NUMA_NO_NODE)
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&& likely(!rcu_access_pointer(flow->stats[node]))) {
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/* Try to allocate node-specific stats. */
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if (likely(flow->stats_last_writer != -1) &&
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likely(!rcu_access_pointer(flow->stats[cpu]))) {
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/* Try to allocate CPU-specific stats. */
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struct flow_stats *new_stats;
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new_stats =
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@ -114,12 +116,12 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags,
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new_stats->tcp_flags = tcp_flags;
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spin_lock_init(&new_stats->lock);
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rcu_assign_pointer(flow->stats[node],
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rcu_assign_pointer(flow->stats[cpu],
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new_stats);
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goto unlock;
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}
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}
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flow->stats_last_writer = node;
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flow->stats_last_writer = cpu;
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}
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}
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@ -136,15 +138,15 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
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struct ovs_flow_stats *ovs_stats,
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unsigned long *used, __be16 *tcp_flags)
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{
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int node;
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int cpu;
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*used = 0;
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*tcp_flags = 0;
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memset(ovs_stats, 0, sizeof(*ovs_stats));
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/* We open code this to make sure node 0 is always considered */
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for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map)) {
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struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]);
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/* We open code this to make sure cpu 0 is always considered */
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for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask)) {
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struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[cpu]);
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if (stats) {
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/* Local CPU may write on non-local stats, so we must
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@ -164,11 +166,11 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
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/* Called with ovs_mutex. */
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void ovs_flow_stats_clear(struct sw_flow *flow)
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{
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int node;
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int cpu;
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/* We open code this to make sure node 0 is always considered */
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for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map)) {
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struct flow_stats *stats = ovsl_dereference(flow->stats[node]);
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/* We open code this to make sure cpu 0 is always considered */
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for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask)) {
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struct flow_stats *stats = ovsl_dereference(flow->stats[cpu]);
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if (stats) {
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spin_lock_bh(&stats->lock);
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@ -178,14 +178,14 @@ struct sw_flow {
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struct hlist_node node[2];
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u32 hash;
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} flow_table, ufid_table;
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int stats_last_writer; /* NUMA-node id of the last writer on
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int stats_last_writer; /* CPU id of the last writer on
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* 'stats[0]'.
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*/
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struct sw_flow_key key;
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struct sw_flow_id id;
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struct sw_flow_mask *mask;
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struct sw_flow_actions __rcu *sf_acts;
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struct flow_stats __rcu *stats[]; /* One for each NUMA node. First one
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struct flow_stats __rcu *stats[]; /* One for each CPU. First one
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* is allocated at flow creation time,
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* the rest are allocated on demand
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* while holding the 'stats[0].lock'.
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@ -32,6 +32,7 @@
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#include <linux/module.h>
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#include <linux/in.h>
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#include <linux/rcupdate.h>
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#include <linux/cpumask.h>
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#include <linux/if_arp.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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@ -79,17 +80,12 @@ struct sw_flow *ovs_flow_alloc(void)
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{
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struct sw_flow *flow;
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struct flow_stats *stats;
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int node;
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flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
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flow = kmem_cache_zalloc(flow_cache, GFP_KERNEL);
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if (!flow)
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return ERR_PTR(-ENOMEM);
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flow->sf_acts = NULL;
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flow->mask = NULL;
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flow->id.unmasked_key = NULL;
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flow->id.ufid_len = 0;
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flow->stats_last_writer = NUMA_NO_NODE;
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flow->stats_last_writer = -1;
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/* Initialize the default stat node. */
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stats = kmem_cache_alloc_node(flow_stats_cache,
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@ -102,10 +98,6 @@ struct sw_flow *ovs_flow_alloc(void)
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RCU_INIT_POINTER(flow->stats[0], stats);
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for_each_node(node)
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if (node != 0)
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RCU_INIT_POINTER(flow->stats[node], NULL);
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return flow;
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err:
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kmem_cache_free(flow_cache, flow);
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@ -142,17 +134,17 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
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static void flow_free(struct sw_flow *flow)
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{
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int node;
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int cpu;
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if (ovs_identifier_is_key(&flow->id))
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kfree(flow->id.unmasked_key);
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if (flow->sf_acts)
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ovs_nla_free_flow_actions((struct sw_flow_actions __force *)flow->sf_acts);
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/* We open code this to make sure node 0 is always considered */
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for (node = 0; node < MAX_NUMNODES; node = next_node(node, node_possible_map))
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if (node != 0 && flow->stats[node])
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/* We open code this to make sure cpu 0 is always considered */
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for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpu_possible_mask))
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if (flow->stats[cpu])
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kmem_cache_free(flow_stats_cache,
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(struct flow_stats __force *)flow->stats[node]);
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(struct flow_stats __force *)flow->stats[cpu]);
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kmem_cache_free(flow_cache, flow);
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}
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@ -757,7 +749,7 @@ int ovs_flow_init(void)
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BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
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flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
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+ (nr_node_ids
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+ (nr_cpu_ids
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* sizeof(struct flow_stats *)),
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0, 0, NULL);
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if (flow_cache == NULL)
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