diff mbox series

[net-next,v5,1/1] net:openvswitch:reduce cpu_used_mask memory

Message ID OS3P286MB22955AB6FF67B67778343FEDF5D79@OS3P286MB2295.JPNP286.PROD.OUTLOOK.COM (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next,v5,1/1] net:openvswitch:reduce cpu_used_mask memory | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning CHECK: Alignment should match open parenthesis
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

缘 陶 Feb. 3, 2023, 8:52 a.m. UTC
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

cpumask 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 <taoyuan_eddy@hotmail.com>
---
 net/openvswitch/flow.c       | 9 ++++++---
 net/openvswitch/flow.h       | 2 +-
 net/openvswitch/flow_table.c | 8 +++++---
 3 files changed, 12 insertions(+), 7 deletions(-)

Comments

Jiri Pirko Feb. 3, 2023, 9 a.m. UTC | #1
Fri, Feb 03, 2023 at 09:52:56AM CET, taoyuan_eddy@hotmail.com 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
>
>cpumask 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 <taoyuan_eddy@hotmail.com>

Eddy, could you please slow down a bit? Why did you send v5 right
after v4? Could you please always put a changelog to the patch
submitted to contain info about changes in between the
submitted version?

Thanks!
Jiri Pirko Feb. 3, 2023, 11:55 a.m. UTC | #2
Fri, Feb 03, 2023 at 10:03:28AM CET, taoyuan_eddy@hotmail.com wrote:
>sorry, Jiri, my bad, will hold on before the next submission/hope it is the final one

Don't top-post please. So what is the change comparing to v4?


>
>eddy
>________________________________
>发件人: Jiri Pirko <jiri@resnulli.us>
>发送时间: 2023年2月3日 9:00
>收件人: Eddy Tao <taoyuan_eddy@hotmail.com>
>抄送: netdev@vger.kernel.org <netdev@vger.kernel.org>; Pravin B Shelar <pshelar@ovn.org>; David S. Miller <davem@davemloft.net>; Eric Dumazet <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; dev@openvswitch.org <dev@openvswitch.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>
>主题: Re: [PATCH net-next v5 1/1] net:openvswitch:reduce cpu_used_mask memory
>
>Fri, Feb 03, 2023 at 09:52:56AM CET, taoyuan_eddy@hotmail.com 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
>>
>>cpumask 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 <taoyuan_eddy@hotmail.com>
>
>Eddy, could you please slow down a bit? Why did you send v5 right
>after v4? Could you please always put a changelog to the patch
>submitted to contain info about changes in between the
>submitted version?
>
>Thanks!
>
diff mbox series

Patch

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index e20d1a973417..a56483eda015 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..dc6a174c3194 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -87,11 +87,12 @@  struct sw_flow *ovs_flow_alloc(void)
 	if (!stats)
 		goto err;
 
+	flow->cpu_used_mask = (struct cpumask *)&flow->stats[nr_cpu_ids];
 	spin_lock_init(&stats->lock);
 
 	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;