Bug #91516 innodb_buffer_pool_size change regular
Submitted: 2 Jul 2018 9:03 Modified: 24 Jul 2018 19:10
Reporter: Xianglong Kou Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:8.0.11 OS:Any (3.10.0-229.el7.x86_64)
Assigned to: CPU Architecture:x86

[2 Jul 2018 9:03] Xianglong Kou
Description:
document link 
https://dev.mysql.com/doc/refman/8.0/en/innodb-buffer-pool-resize.html

Buffer pool size must always be equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances. If you configure innodb_buffer_pool_size to a value that is not equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances, buffer pool size is automatically adjusted to a value that is equal to or a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances that is not less than the specified buffer pool size.

the doc say "not less than the specified buffer pool size. ","not less than" realy ? 

How to repeat:
[root@dblion ~]# tail -n 2 /etc/my.cnf 
innodb_buffer_pool_size=2415919105
innodb_buffer_pool_instances=2
[root@dblion ~]# 
[root@dblion ~]# service mysqld restart

mysql> select @@innodb_buffer_pool_size;
+---------------------------+
| @@innodb_buffer_pool_size |
+---------------------------+
|                2415919104 |
+---------------------------+
1 row in set (0.00 sec)

mysql>

why ? the innodb_buffer_pool_size  value change to small ?
2415919105 to 2415919104

[root@dblion ~]# tail -n 2 /etc/my.cnf 
innodb_buffer_pool_size=2684354559
innodb_buffer_pool_instances=2
[root@dblion ~]# service mysqld restart
mysql> select @@innodb_buffer_pool_size;
+---------------------------+
| @@innodb_buffer_pool_size |
+---------------------------+
|                2684354560 |
+---------------------------+
1 row in set (0.00 sec)

mysql>

why ? the innodb_buffer_pool_size  value change to big ?
2684354559 to 2684354560
[2 Jul 2018 12:19] MySQL Verification Team
Hi,

Thank you for your bug report.

If you look at the code you will easily see that this variable is always rounded to a value that depends on the page size. However, I do not see this mentioned anywhere in our documentation.

Verified as a documentation bug.
[24 Jul 2018 19:10] Daniel Price
Posted by developer:
 
The referenced content has been revised. Changes should appear online within 24 hours.
Thank you for the bug report.