branches/zip:

Fix a bug in manipulating the variable innodb_old_blocks_pct:

for any value assigned it got that value -1, except for 75. When
assigned 75, it got 75.

  mysql> set global innodb_old_blocks_pct=15;
  Query OK, 0 rows affected (0.00 sec)
  
  mysql> show variables like 'innodb_old_blocks_pct';
  +-----------------------+-------+
  | Variable_name         | Value |
  +-----------------------+-------+
  | innodb_old_blocks_pct | 14    | 
  +-----------------------+-------+
  1 row in set (0.00 sec)
  
  mysql> set global innodb_old_blocks_pct=75;
  Query OK, 0 rows affected (0.00 sec)
  
  mysql> show variables like 'innodb_old_blocks_pct';
  +-----------------------+-------+
  | Variable_name         | Value |
  +-----------------------+-------+
  | innodb_old_blocks_pct | 75    | 
  +-----------------------+-------+

After the fix it gets exactly what was assigned.

Approved by:	Marko (via IM)

buf/buf0lru.c

@@ -1866,7 +1866,9 @@ buf_LRU_old_ratio_update(
 		buf_LRU_old_ratio = ratio;
 	}
 
-	return(ratio * 100 / BUF_LRU_OLD_RATIO_DIV);
+	/* the reverse of 
+	ratio = old_pct * BUF_LRU_OLD_RATIO_DIV / 100 */
+	return((uint) (ratio * 100 / (double) BUF_LRU_OLD_RATIO_DIV + 0.5));
 }
 
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