Subject locate_space on busy pages
Author Dimitry Sibiryakov
Hello, All.

Currently when locate_space() looks for space, it waits for exclusive
lock on candidate page before calling find_space() to check whether the
candidate can become the target for data placement. It has sense for
preferable pages. But wouldn't it better to skip locked non-preferable
pages if they are currently busy?
I guess this change can increase FB performance on high load.