idiag: provide a hash function for idiag objects

Without ->oo_keygen, libnl will use linear search
for cache objects. This is extremely slow for idiag
when we have a lot of TCP connections. Provide a
hash function for idiag so that libnl will be able
to lookup a hashtable.

http://lists.infradead.org/pipermail/libnl/2014-November/001715.html

Cc: Thomas Graf <tgraf@suug.ch>
Cc: Thomas Haller <thaller@redhat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Thomas Haller <thaller@redhat.com>

diff --git a/lib/idiag/idiag_msg_obj.c b/lib/idiag/idiag_msg_obj.c
index 19e6c5be6ff36a0f594f71dbc0db89f052ebd900..92a98e918c524365d257d2a8b0dd65f19ddb1e4e 100644 (file)
--- a/lib/idiag/idiag_msg_obj.c
+++ b/lib/idiag/idiag_msg_obj.c
@@ -10,6 +10,7 @@
  */
 
 #include <netlink-private/netlink.h>
+#include <netlink/hashtable.h>
 #include <netlink/idiag/msg.h>
 #include <netlink/idiag/meminfo.h>
 #include <netlink/idiag/vegasinfo.h>
@@ -710,6 +711,32 @@ errout_nomem:
        goto errout;
 }
 
+static void idiagnl_keygen(struct nl_object *obj, uint32_t *hashkey,
+        uint32_t table_sz)
+{
+       struct idiagnl_msg *msg = (struct idiagnl_msg *)obj;
+       unsigned int key_sz;
+       struct idiagnl_hash_key {
+               uint8_t family;
+               uint8_t state;
+               uint16_t sport;
+               uint16_t dport;
+       } __attribute__((packed)) key;
+
+       key_sz = sizeof(key);
+       key.family = msg->idiag_family;
+       key.state = msg->idiag_state;
+       key.sport = msg->idiag_sport;
+       key.dport = msg->idiag_dport;
+
+       *hashkey = nl_hash(&key, key_sz, 0) % table_sz;
+
+       NL_DBG(5, "idiagnl %p key (fam %d state %d sport %d dport %d) keysz %d, hash 0x%x\n",
+              msg, key.family, key.state, key.sport, key.dport, key_sz, *hashkey);
+
+       return;
+}
+
 /** @cond SKIP */
 struct nl_object_ops idiagnl_msg_obj_ops = {
        .oo_name                         = "idiag/idiag_msg",
@@ -721,6 +748,7 @@ struct nl_object_ops idiagnl_msg_obj_ops = {
                [NL_DUMP_DETAILS]        = idiag_msg_dump_details,
                [NL_DUMP_STATS]          = idiag_msg_dump_stats,
        },
+       .oo_keygen                      = idiagnl_keygen,
        .oo_attrs2str                   = idiagnl_attrs2str,
        .oo_id_attrs                    = (IDIAG_ATTR_INFO)
 };