ovsdb: Fix copying weak references into transaction history.

Transaction history is used only to construct row data updates for
clients, it's not used for checking data integrity, hence it doesn't
need a copy of weak references.

Not copying this data saves a lot of CPU cycles and memory in some
cases.  For example, in 250-node density-heavy scenario in ovn-heater
these references can take up to 70% of RSS, which is about 8 GB of
essentially wasted memory as reported by valgrind massif:

 -------------------------------------------------------------------------------
   n        time(i)         total(B)    useful-heap(B) extra-heap(B)   stacks(B)
 -------------------------------------------------------------------------------
  20 1,011,495,832,314  11,610,557,104  10,217,785,620 1,392,771,484        0

 88.00% (10,217,785,620B) (heap allocation functions) malloc/new/new[]
 ->70.47% (8,181,819,064B) 0x455372: xcalloc__ (util.c:121)
   ->70.07% (8,135,785,424B) 0x41609D: ovsdb_weak_ref_clone (row.c:66)
     ->70.07% (8,135,785,424B) 0x41609D: ovsdb_row_clone (row.c:151)
       ->34.74% (4,034,041,440B) 0x41B7C9: ovsdb_txn_clone (transaction.c:1124)
       | ->34.74% (4,034,041,440B) 0x41B7C9: ovsdb_txn_add_to_history (transaction.c:1163)
       |   ->34.74% (4,034,041,440B) 0x41B7C9: ovsdb_txn_replay_commit (transaction.c:1198)
       |     ->34.74% (4,034,041,440B) 0x408C35: parse_txn (ovsdb-server.c:633)
       |       ->34.74% (4,034,041,440B) 0x408C35: read_db (ovsdb-server.c:663)
       |         ->34.74% (4,034,041,440B) 0x406C9D: main_loop (ovsdb-server.c:238)
       |           ->34.74% (4,034,041,440B) 0x406C9D: main (ovsdb-server.c:500)
       |
       ->34.74% (4,034,041,440B) 0x41B7DE: ovsdb_txn_clone (transaction.c:1125)
         ->34.74% (4,034,041,440B) 0x41B7DE: ovsdb_txn_add_to_history (transaction.c:1163)
           ->34.74% (4,034,041,440B) 0x41B7DE: ovsdb_txn_replay_commit (transaction.c:1198)
             ->34.74% (4,034,041,440B) 0x408C35: parse_txn (ovsdb-server.c:633)
               ->34.74% (4,034,041,440B) 0x408C35: read_db (ovsdb-server.c:663)
                 ->34.74% (4,034,041,440B) 0x406C9D: main_loop (ovsdb-server.c:238)
                   ->34.74% (4,034,041,440B) 0x406C9D: main (ovsdb-server.c:500)

Replacing ovsdb_row_clone() with ovsdb_row_datum_clone() to avoid
cloning unnecessary metadata.  The ovsdb_txn_clone() function re-named
to avoid issues if it will be re-used in the future for some other
use-case.

Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/ovsdb/transaction.c b/ovsdb/transaction.c
index 6864fe099..d8d677d31 100644
--- a/ovsdb/transaction.c
+++ b/ovsdb/transaction.c
@@ -1098,7 +1098,7 @@ ovsdb_txn_precommit(struct ovsdb_txn *txn)
 }
 
 static struct ovsdb_txn*
-ovsdb_txn_clone(const struct ovsdb_txn *txn)
+ovsdb_txn_clone_for_history(const struct ovsdb_txn *txn)
 {
     struct ovsdb_txn *txn_cloned = xzalloc(sizeof *txn_cloned);
     ovs_list_init(&txn_cloned->txn_tables);
@@ -1121,8 +1121,8 @@ ovsdb_txn_clone(const struct ovsdb_txn *txn)
 
             r_cloned->uuid = r->uuid;
             r_cloned->table = r->table;
-            r_cloned->old = r->old ? ovsdb_row_clone(r->old) : NULL;
-            r_cloned->new = r->new ? ovsdb_row_clone(r->new) : NULL;
+            r_cloned->old = r->old ? ovsdb_row_datum_clone(r->old) : NULL;
+            r_cloned->new = r->new ? ovsdb_row_datum_clone(r->new) : NULL;
             memcpy(&r_cloned->changed, &r->changed, bitmap_n_bytes(n_columns));
             hmap_insert(&t_cloned->txn_rows, &r_cloned->hmap_node,
                         uuid_hash(&r_cloned->uuid));
@@ -1160,7 +1160,7 @@ ovsdb_txn_add_to_history(struct ovsdb_txn *txn)
 {
     if (txn->db->need_txn_history) {
         struct ovsdb_txn_history_node *node = xzalloc(sizeof *node);
-        node->txn = ovsdb_txn_clone(txn);
+        node->txn = ovsdb_txn_clone_for_history(txn);
         ovs_list_push_back(&txn->db->txn_history, &node->node);
         txn->db->n_txn_history++;
         txn->db->n_txn_history_atoms += txn->n_atoms;