MySQL Bugs: #72184: InnoDB buffer pool status variables (Innodb_buffer_pool

Bug #72184	InnoDB buffer pool status variables (Innodb_buffer_pool_pages*)
Submitted:	1 Apr 2014 12:58	Modified:	2 Apr 2014 17:55
Reporter:	Ceri Williams	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S3 (Non-critical)
Version:	5.5, 5.6	OS:	Linux
Assigned to:		CPU Architecture:	Any

Description:
According to the manual:

Innodb_buffer_pool_pages_data:  The number of pages in the InnoDB buffer pool containing data. The number includes both dirty and clean pages.
Innodb_buffer_pool_pages_free:  The number of free pages in the InnoDB buffer pool.
Innodb_buffer_pool_pages_total: The total size of the InnoDB buffer pool, in pages.

So, the following should be true:

Innodb_buffer_pool_pages_data + Innodb_buffer_pool_pages_free = Innodb_buffer_pool_pages_total

However, this does not appear to be the case, which means either the documentation is unclear or the variables do not represent the data that they should, e.g.

Innodb_buffer_pool_pages_data  = 7254112
Innodb_buffer_pool_pages_free  = 34816
Innodb_buffer_pool_pages_total = 4456414

7254112 + 34816   = 7288928
7288928 / 4456414 = 1.63

How to repeat:
bp_data=$(mysql -Nsq -e"show global status like 'Innodb_buffer_pool_pages_data'"|tr '\t' , )
bp_total=$(mysql -Nsq -e"show global status like 'Innodb_buffer_pool_pages_total'"|tr '\t' , )
bp_free=$(mysql -Nsq -e"show global status like 'Innodb_buffer_pool_pages_free'"|tr '\t' , )

echo ${bp_data}
echo ${bp_total}
echo ${bp_free}

echo "scale=2; ( $(echo ${bp_data} | cut -f2 -d,) + $(echo ${bp_free} | cut -f2 -d,) ) / $(echo ${bp_total} | cut -f2 -d,)" | bc

Suggested fix:
Either fix the data for the variables, or clarify the documentation.

What is the value of Innodb_buffer_pool_pages_misc and does it explain the difference?

Valeriy was right to ask for innodb_buffer_pool_pages_misc.

This bug is probably a duplicate of this one :

http://bugs.mysql.com/bug.php?id=59550

It occurs when using compressed pages from 5.1 + InnoDB plugin.