Use actual CPU number instead of hardcoded value to decide the size
of 'cpu_used_mask' in 'struct sw_flow'. Below is the reason.
'struct cpumask cpu_used_mask' is embedded in struct sw_flow.
Its size is hardcoded to CONFIG_NR_CPUS bits, which can be
8192 by default, it costs memory and slows down ovs_flow_alloc.
To address this:
Redefine cpu_used_mask to pointer.
Append cpumask_size() bytes after 'stat' to hold cpumask.
Initialization cpu_used_mask right after stats_last_writer.
APIs like cpumask_next and cpumask_set_cpu never access bits
beyond cpu count, cpumask_size() bytes of memory is enough.
Signed-off-by: Eddy Tao <[email protected]>
---
V7 -> V8: add blanc space after colon in subject line
V6 -> V7: initialize cpu_used_mask after stats_last_writer
V5 -> V6: add tab to align the wrapped cpumask_set_cpu call
V4 -> V5: fix max-line-length warning
V3 -> V4: no change, sorry, my bad
V2 -> V3: add 'net-next' in prefix
fix max-line-length warning
remove the comment
V1 -> V2: make comment imperitive
remove unnecessary parentheses
net/openvswitch/flow.c | 9 ++++++---
net/openvswitch/flow.h | 2 +-
net/openvswitch/flow_table.c | 8 +++++---
3 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index e20d1a973417..416976f70322 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -107,7 +107,8 @@ 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);
+ cpumask_set_cpu(cpu,
+ flow->cpu_used_mask);
goto unlock;
}
}
@@ -135,7 +136,8 @@ 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, &flow->cpu_used_mask)) {
+ for (cpu = 0; cpu < nr_cpu_ids;
+ cpu = cpumask_next(cpu, flow->cpu_used_mask)) {
struct sw_flow_stats *stats = rcu_dereference_ovsl(flow->stats[cpu]);
if (stats) {
@@ -159,7 +161,8 @@ 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, &flow->cpu_used_mask)) {
+ for (cpu = 0; cpu < nr_cpu_ids;
+ cpu = cpumask_next(cpu, flow->cpu_used_mask)) {
struct sw_flow_stats *stats = ovsl_dereference(flow->stats[cpu]);
if (stats) {
diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h
index 073ab73ffeaa..b5711aff6e76 100644
--- a/net/openvswitch/flow.h
+++ b/net/openvswitch/flow.h
@@ -229,7 +229,7 @@ struct sw_flow {
*/
struct sw_flow_key key;
struct sw_flow_id id;
- struct cpumask cpu_used_mask;
+ struct cpumask *cpu_used_mask;
struct sw_flow_mask *mask;
struct sw_flow_actions __rcu *sf_acts;
struct sw_flow_stats __rcu *stats[]; /* One for each CPU. First one
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 0a0e4c283f02..791504b7f42b 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -79,6 +79,7 @@ struct sw_flow *ovs_flow_alloc(void)
return ERR_PTR(-ENOMEM);
flow->stats_last_writer = -1;
+ flow->cpu_used_mask = (struct cpumask *)&flow->stats[nr_cpu_ids];
/* Initialize the default stat node. */
stats = kmem_cache_alloc_node(flow_stats_cache,
@@ -91,7 +92,7 @@ struct sw_flow *ovs_flow_alloc(void)
RCU_INIT_POINTER(flow->stats[0], stats);
- cpumask_set_cpu(0, &flow->cpu_used_mask);
+ cpumask_set_cpu(0, flow->cpu_used_mask);
return flow;
err:
@@ -115,7 +116,7 @@ static void flow_free(struct sw_flow *flow)
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, &flow->cpu_used_mask)) {
+ cpu = cpumask_next(cpu, flow->cpu_used_mask)) {
if (flow->stats[cpu])
kmem_cache_free(flow_stats_cache,
(struct sw_flow_stats __force *)flow->stats[cpu]);
@@ -1196,7 +1197,8 @@ int ovs_flow_init(void)
flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
+ (nr_cpu_ids
- * sizeof(struct sw_flow_stats *)),
+ * sizeof(struct sw_flow_stats *))
+ + cpumask_size(),
0, 0, NULL);
if (flow_cache == NULL)
return -ENOMEM;
--
2.27.0
On 5 Feb 2023, at 2:35, Eddy Tao wrote:
> Use actual CPU number instead of hardcoded value to decide the size
> of 'cpu_used_mask' in 'struct sw_flow'. Below is the reason.
>
> 'struct cpumask cpu_used_mask' is embedded in struct sw_flow.
> Its size is hardcoded to CONFIG_NR_CPUS bits, which can be
> 8192 by default, it costs memory and slows down ovs_flow_alloc.
>
> To address this:
> Redefine cpu_used_mask to pointer.
> Append cpumask_size() bytes after 'stat' to hold cpumask.
> Initialization cpu_used_mask right after stats_last_writer.
>
> APIs like cpumask_next and cpumask_set_cpu never access bits
> beyond cpu count, cpumask_size() bytes of memory is enough.
>
> Signed-off-by: Eddy Tao <[email protected]>
The changes look good to me. Hopefully this is the last revision ;)
Acked-by: Eelco Chaudron <[email protected]>
Yes, Eelco, this is the last revision and no further comments for
revision came in
eddy
On 2023/2/6 19:21, Eelco Chaudron wrote:
>
> On 5 Feb 2023, at 2:35, Eddy Tao wrote:
>
>> Use actual CPU number instead of hardcoded value to decide the size
>> of 'cpu_used_mask' in 'struct sw_flow'. Below is the reason.
>>
>> 'struct cpumask cpu_used_mask' is embedded in struct sw_flow.
>> Its size is hardcoded to CONFIG_NR_CPUS bits, which can be
>> 8192 by default, it costs memory and slows down ovs_flow_alloc.
>>
>> To address this:
>> Redefine cpu_used_mask to pointer.
>> Append cpumask_size() bytes after 'stat' to hold cpumask.
>> Initialization cpu_used_mask right after stats_last_writer.
>>
>> APIs like cpumask_next and cpumask_set_cpu never access bits
>> beyond cpu count, cpumask_size() bytes of memory is enough.
>>
>> Signed-off-by: Eddy Tao <[email protected]>
> The changes look good to me. Hopefully this is the last revision ;)
>
> Acked-by: Eelco Chaudron <[email protected]>
>
Hello:
This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <[email protected]>:
On Sun, 5 Feb 2023 09:35:37 +0800 you wrote:
> Use actual CPU number instead of hardcoded value to decide the size
> of 'cpu_used_mask' in 'struct sw_flow'. Below is the reason.
>
> 'struct cpumask cpu_used_mask' is embedded in struct sw_flow.
> Its size is hardcoded to CONFIG_NR_CPUS bits, which can be
> 8192 by default, it costs memory and slows down ovs_flow_alloc.
>
> [...]
Here is the summary with links:
- [net-next,v8,1/1] net: openvswitch: reduce cpu_used_mask memory
https://git.kernel.org/netdev/net-next/c/15ea59a0e9bf
You are awesome, thank you!
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