On 22 Jul 2020, at 21:22, Florian Westphal wrote:

Eelco Chaudron [off-list ref] wrote:

quoted

This patch makes the masks cache size configurable, or with
a size of 0, disable it.

Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
 include/uapi/linux/openvswitch.h |    1
 net/openvswitch/datapath.c       |   11 +++++
 net/openvswitch/flow_table.c     |   86 
++++++++++++++++++++++++++++++++++----
 net/openvswitch/flow_table.h     |   10 ++++
 4 files changed, 98 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/openvswitch.h 

b/include/uapi/linux/openvswitch.h
index 7cb76e5ca7cf..8300cc29dec8 100644

--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h

@@ -86,6 +86,7 @@ enum ovs_datapath_attr {
 	OVS_DP_ATTR_MEGAFLOW_STATS,	/* struct ovs_dp_megaflow_stats */
 	OVS_DP_ATTR_USER_FEATURES,	/* OVS_DP_F_*  */
 	OVS_DP_ATTR_PAD,
+	OVS_DP_ATTR_MASKS_CACHE_SIZE,

This new attr should probably get an entry in
datapath.c datapath_policy[].

Yes, I should have, will fix in v2.

quoted

--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c

@@ -1535,6 +1535,10 @@ static int ovs_dp_cmd_fill_info(struct 

datapath *dp, struct sk_buff *skb,
 	if (nla_put_u32(skb, OVS_DP_ATTR_USER_FEATURES, dp->user_features))
 		goto nla_put_failure;

+	if (nla_put_u32(skb, OVS_DP_ATTR_MASKS_CACHE_SIZE,
+			ovs_flow_tbl_masks_cache_size(&dp->table)))
+		goto nla_put_failure;
+
 	genlmsg_end(skb, ovs_header);
 	return 0;

ovs_dp_cmd_msg_size() should add another nla_total_size(sizeof(u32))
to make sure there is enough space.

Same as above

quoted

+	if (a[OVS_DP_ATTR_MASKS_CACHE_SIZE]) {
+		u32 cache_size;
+
+		cache_size = nla_get_u32(a[OVS_DP_ATTR_MASKS_CACHE_SIZE]);
+		ovs_flow_tbl_masks_cache_resize(&dp->table, cache_size);
+	}

I see a 0 cache size is legal (turns it off) and that the allocation
path has a few sanity checks as well.

Would it make sense to add min/max policy to datapath_policy[] for 
this
as well?

Yes I could add the following:

@@ -1906,7 +1906,8 @@ static const struct nla_policy 

datapath_policy[OVS_DP_ATTR_MAX + 1] = {
         [OVS_DP_ATTR_NAME] = { .type = NLA_NUL_STRING, .len = IFNAMSIZ 
- 1 },
         [OVS_DP_ATTR_UPCALL_PID] = { .type = NLA_U32 },
         [OVS_DP_ATTR_USER_FEATURES] = { .type = NLA_U32 },
+       [OVS_DP_ATTR_MASKS_CACHE_SIZE] =  NLA_POLICY_RANGE(NLA_U32, 0,
+               PCPU_MIN_UNIT_SIZE / sizeof(struct mask_cache_entry)),
  };

Let me know your thoughts