Upstream commit:
commit c4b2bf6b4a35348fe6d1eb06928eb68d7b9d99a9
Author: Tonghao Zhang <[email protected]>
Date: Mon Jul 17 23:28:06 2017 -0700
openvswitch: Optimize operations for OvS flow_stats.
When calling the flow_free() to free the flow, we call many times
(cpu_possible_mask, eg. 128 as default) cpumask_next(). That will
take up our CPU usage if we call the flow_free() frequently.
When we put all packets to userspace via upcall, and OvS will send
them back via netlink to ovs_packet_cmd_execute(will call flow_free).
The test topo is shown as below. VM01 sends TCP packets to VM02,
and OvS forward packtets. When testing, we use perf to report the
system performance.
VM01 --- OvS-VM --- VM02
Without this patch, perf-top show as below: The flow_free() is
3.02% CPU usage.
4.23% [kernel] [k] _raw_spin_unlock_irqrestore
3.62% [kernel] [k] __do_softirq
3.16% [kernel] [k] __memcpy
3.02% [kernel] [k] flow_free
2.42% libc-2.17.so [.] __memcpy_ssse3_back
2.18% [kernel] [k] copy_user_generic_unrolled
2.17% [kernel] [k] find_next_bit
When applied this patch, perf-top show as below: Not shown on
the list anymore.
4.11% [kernel] [k] _raw_spin_unlock_irqrestore
3.79% [kernel] [k] __do_softirq
3.46% [kernel] [k] __memcpy
2.73% libc-2.17.so [.] __memcpy_ssse3_back
2.25% [kernel] [k] copy_user_generic_unrolled
1.89% libc-2.17.so [.] _int_malloc
1.53% ovs-vswitchd [.] xlate_actions
With this patch, the TCP throughput(we dont use Megaflow Cache
+ Microflow Cache) between VMs is 1.18Gbs/sec up to 1.30Gbs/sec
(maybe ~10% performance improve).
This patch adds cpumask struct, the cpu_used_mask stores the cpu_id
that the flow used. And we only check the flow_stats on the cpu we
used, and it is unncessary to check all possible cpu when getting,
cleaning, and updating the flow_stats. Adding the cpu_used_mask to
sw_flow struct does’t increase the cacheline number.
Signed-off-by: Tonghao Zhang <[email protected]>
Acked-by: Pravin B Shelar <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Tonghao Zhang <[email protected]>
---
datapath/flow.c | 7 ++++---
datapath/flow.h | 2 ++
datapath/flow_table.c | 4 +++-
3 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/datapath/flow.c b/datapath/flow.c
index 20582df..a23e147 100644
--- a/datapath/flow.c
+++ b/datapath/flow.c
@@ -71,7 +71,7 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16
tcp_flags,
const struct sk_buff *skb)
{
struct flow_stats *stats;
- int cpu = smp_processor_id();
+ unsigned int cpu = smp_processor_id();
int len = skb->len + (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
stats = rcu_dereference(flow->stats[cpu]);
@@ -116,6 +116,7 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16
tcp_flags,
rcu_assign_pointer(flow->stats[cpu],
new_stats);
+ cpumask_set_cpu(cpu,
&flow->cpu_used_mask);
goto unlock;
}
}
@@ -143,7 +144,7 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
memset(ovs_stats, 0, sizeof(*ovs_stats));
/* 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)) {
+ for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu,
&flow->cpu_used_mask)) {
struct flow_stats *stats =
rcu_dereference_ovsl(flow->stats[cpu]);
if (stats) {
@@ -167,7 +168,7 @@ void ovs_flow_stats_clear(struct sw_flow *flow)
int cpu;
/* 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)) {
+ for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu,
&flow->cpu_used_mask)) {
struct flow_stats *stats = ovsl_dereference(flow->stats[cpu]);
if (stats) {
diff --git a/datapath/flow.h b/datapath/flow.h
index 07af912..0796b09 100644
--- a/datapath/flow.h
+++ b/datapath/flow.h
@@ -31,6 +31,7 @@
#include <linux/jiffies.h>
#include <linux/time.h>
#include <linux/flex_array.h>
+#include <linux/cpumask.h>
#include <net/inet_ecn.h>
#include <net/ip_tunnels.h>
#include <net/dst_metadata.h>
@@ -218,6 +219,7 @@ struct sw_flow {
*/
struct sw_flow_key key;
struct sw_flow_id id;
+ struct cpumask cpu_used_mask;
struct sw_flow_mask *mask;
struct sw_flow_actions __rcu *sf_acts;
struct flow_stats __rcu *stats[]; /* One for each CPU. First one
diff --git a/datapath/flow_table.c b/datapath/flow_table.c
index 6fe3739..47057a1 100644
--- a/datapath/flow_table.c
+++ b/datapath/flow_table.c
@@ -104,6 +104,8 @@ struct sw_flow *ovs_flow_alloc(void)
RCU_INIT_POINTER(flow->stats[0], stats);
+ cpumask_set_cpu(0, &flow->cpu_used_mask);
+
return flow;
err:
kmem_cache_free(flow_cache, flow);
@@ -147,7 +149,7 @@ static void flow_free(struct sw_flow *flow)
if (flow->sf_acts)
ovs_nla_free_flow_actions((struct sw_flow_actions __force
*)flow->sf_acts);
/* 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))
+ for (cpu = 0; cpu < nr_cpu_ids; cpu = cpumask_next(cpu,
&flow->cpu_used_mask))
if (flow->stats[cpu])
kmem_cache_free(flow_stats_cache,
rcu_dereference_raw(flow->stats[cpu]));
--
1.8.3.1
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