At startup, mysql will use some memory.
Some of the memory is pre-allocated for "key_buffer" and "innodb_buffer_pool_size" ( and other things ).
Is it possible to determine how much memory is pre-allocated ( for data ) and how much memory has been used ?
Let me take an example to explain what I want to ask. After I start mysql server, it use some memory as part of "key buffer". Say, I set key_buffer=1G. Maybe at startup, mysql server has pre-allocated 200M as "key buffer". Then when users begin to do queries against this server. The server can only get extra 800M as "key buffer". 200 is a random number I pick. And apparently besides key_buffer, there are other things ( such as innnodb buffer ) What I want to know is the exact size or the way to calculate it.
Hope I've explained myself clearly.