acl-plugin: tm: avoid hash calculation dependency on a memory store operation
A small store into a middle of a larger structure that was subsequently
loaded for calculating the bihash key was noticeably impacting the performance.
@@ -605,7 +605,15 @@ multi_acl_match_get_applied_ace_index (acl_main_t * am, int is_ip6, fa_5tuple_t
*pkey++ = *pmatch++ & *pmask++;
*pkey++ = *pmatch++ & *pmask++;
- kv_key->pkt.mask_type_index_lsb = mask_type_index;
+ /*
+ * The use of temporary variable convinces the compiler
+ * to make a u64 write, avoiding the stall on crc32 operation
+ * just a bit later.
+ */
+ fa_packet_info_t tmp_pkt = kv_key->pkt;
+ tmp_pkt.mask_type_index_lsb = mask_type_index;
+ kv_key->pkt.as_u64 = tmp_pkt.as_u64;
+
int res =
clib_bihash_search_inline_2_48_8 (&am->acl_lookup_hash, &kv, &result);
