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>
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 <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>
@@ -72,32 +73,33 @@
{
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 @@
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 @@
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 @@
/* 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);