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>

1 files changed, 9 insertions, 17 deletions

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 957a3c31dbb0..ea7a8073fa02 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -32,6 +32,7 @@
 #include <linux/module.h>
 #include <linux/in.h>
 #include <linux/rcupdate.h>
+#include <linux/cpumask.h>
 #include <linux/if_arp.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
@@ -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)