Improves the performance of OVSDB avoiding the chain
reaction produced when modifing rows with a strong
reference and the pointed rows have more strong
references.
The approach taken was using the change bitmap to avoid
triggering a change count when the column hasn't changed.
One way to trigger the issue is emulating a simple linked list
with strong references within a table, where each new row
points to the previous.
Without the fix OVSDB creates a ovsdb_txn_row (and a copy
of the row) for each row in the table.
With the fix it only creates two ovsdb_txn_row: the new row and
the directly pointed row.
Signed-off-by: Esteban Rodriguez Betancourt <esteb...@hpe.com>
---
ovsdb/transaction.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/ovsdb/transaction.c b/ovsdb/transaction.c
index 84ccfa3..9e12a62 100644
--- a/ovsdb/transaction.c
+++ b/ovsdb/transaction.c
@@ -271,16 +271,18 @@ update_row_ref_count(struct ovsdb_txn *txn, struct
ovsdb_txn_row *r)
const struct ovsdb_column *column = node->data;
struct ovsdb_error *error;
- if (r->old) {
- error = ovsdb_txn_adjust_row_refs(txn, r->old, column, -1);
- if (error) {
- return OVSDB_WRAP_BUG("error decreasing refcount", error);
+ if (bitmap_is_set(r->changed, column->index)) {
+ if (r->old) {
+ error = ovsdb_txn_adjust_row_refs(txn, r->old, column, -1);
+ if (error) {
+ return OVSDB_WRAP_BUG("error decreasing refcount", error);
+ }
}
- }
- if (r->new) {
- error = ovsdb_txn_adjust_row_refs(txn, r->new, column, 1);
- if (error) {
- return error;
+ if (r->new) {
+ error = ovsdb_txn_adjust_row_refs(txn, r->new, column, 1);
+ if (error) {
+ return error;
+ }
}
}
}
--
1.9.1
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