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Re: innodb memory usage vs swap
Posted by: Rick James
Date: September 10, 2010 11:14PM

I asked about huge pages because you mentioned
vm.nr_hugepages = 2048

cat /proc/meminfo |grep Hugepagesize
That might say 2048K

Multiply those together and you get 4GB reserved for huge pages.

mysqld is probably not running --large-pages
Quote

Large page support in MySQL is disabled by default. To enable it, start the server with the --large-pages option. For example, you can use the following lines in your server's my.cnf file:

[mysqld]
large-pages

A guess: The OS preallocated 4GB for huge pages. But no process is using it. Meanwhile the other 4GB is used by mysqld and assorted OS things. But mysqld needs 4GB for the innodb_buffer_pool. So, something has to swap.

See also http://bugs.mysql.com/bug.php?id=43606
http://dev.mysql.com/doc/refman/5.0/en/large-page-support.html

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