Innodb Transportable Tablespaces

When I run:
FLUSH TABLES *** FOR EXPORT
command is executed in few hours, sometime is executed in 1 second, and doesn’t matter how big is table what i’m trying to export.
On mysql bug tracker I found next info:
http://bugs.mysql.com/bug.php?id=68639
“If you have replication running do a stop slave; the flush tables completes in about a minute and a half. If you have other io going to it I am guessing it will still take forever.”
How I can find what IO process is running and stop it?

P.S. When I’m running flush tables for export, server is standalone, and client access is blocked.