MySQL Bugs: #64116: fil_space_get_size called too frequently

Bug #64116	fil_space_get_size called too frequently
Submitted:	23 Jan 2012 20:05	Modified:	24 Jan 2012 8:47
Reporter:	Mark Callaghan	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: InnoDB Plugin storage engine	Severity:	S5 (Performance)
Version:	5.1,5.5,5.6	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	fil_space_get_size, innodb

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Description:
buf_flush_try_neighbors has two calls to fil_space_get_size. This can be converted to one call if the result from the first call is saved. As fil_space_get_mutex locks/unlocks a global mutex (fil_system->mutex) I think this is a good change whether or not it produces a benefit on a benchmark.

        if (high > fil_space_get_size(space)) {
                high = fil_space_get_size(space);
        }

buf_read_ahead_linear also does this

How to repeat:
read the source

Suggested fix:
save the result

Thank you for the problem report. Verified by code review.