This patch is backport of innodb_extra_rseg (XtraDB)
Some update-intentional workloads may not scale performance with “many” CPUs. If the bottle-neck is contention of “rseg→mutex”, this function may help the scale.
(default 0) - The number of extra user rollback segments created when new db is created.
shows information about all rollback segments
| Field | Notes |
|---|---|
| rseg_id | rollback segment id |
| space_id | space where the segment placed |
| page_no | page number of the segment header |
| max_size | max size in pages |
| curr_size | current size in pages |
This example is with innodb_extra_rsegments = 8.
mysql> select * from information_schema.innodb_rseg; +---------+----------+---------+------------+-----------+ | rseg_id | space_id | page_no | max_size | curr_size | +---------+----------+---------+------------+-----------+ | 0 | 0 | 6 | 4294967294 | 1 | | 1 | 0 | 13 | 4294967294 | 2 | | 2 | 0 | 14 | 4294967294 | 1 | | 3 | 0 | 15 | 4294967294 | 1 | | 4 | 0 | 16 | 4294967294 | 1 | | 5 | 0 | 17 | 4294967294 | 1 | | 6 | 0 | 18 | 4294967294 | 1 | | 7 | 0 | 19 | 4294967294 | 1 | | 8 | 0 | 20 | 4294967294 | 1 | +---------+----------+---------+------------+-----------+ 9 rows in set (0.00 sec)