innodb_extra_rseg

Description

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.

Variables Provided

innodb_extra_rsegments

(default 0) - The number of extra user rollback segments created when new db is created.

Information schema added

innodb_rseg

shows information about all rollback segments

FieldNotes
rseg_id rollback segment id
space_id space where the segment placed
zip_size compressed page size in bytes if compressed otherwise 0
page_no page number of the segment header
max_size max size in pages
curr_size current size in pages

Example

This example is with innodb_extra_rsegments = 8.

mysql> select * from information_schema.innodb_rseg;
+---------+----------+----------+---------+------------+-----------+
| rseg_id | space_id | zip_size | page_no | max_size   | curr_size |
+---------+----------+----------+---------+------------+-----------+
|       0 |        0 |        0 |       6 | 4294967294 |         1 |
|       1 |        0 |        0 |      13 | 4294967294 |         2 |
|       2 |        0 |        0 |      14 | 4294967294 |         1 |
|       3 |        0 |        0 |      15 | 4294967294 |         1 |
|       4 |        0 |        0 |      16 | 4294967294 |         1 |
|       5 |        0 |        0 |      17 | 4294967294 |         1 |
|       6 |        0 |        0 |      18 | 4294967294 |         1 |
|       7 |        0 |        0 |      19 | 4294967294 |         1 |
|       8 |        0 |        0 |      20 | 4294967294 |         1 |
+---------+----------+----------+---------+------------+-----------+
9 rows in set (0.00 sec)

Patch information

Author/Origin Percona
Bugs fixed
Dependencies
Introduced in 1.0.2-3

Links

Discussion

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percona-xtradb/patch/innodb_extra_rseg.txt · Last modified: 2009/03/23 23:09 by kinoshita
 
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