Replication Speed

[Miguel Araújo]

Hello.

I want to measure replication speed for a great number of replicas. By that I mean how
soon an event arrives at the slave after being logger to the master's binary log.

So, I've started developing an application to read the replication logs in order to
compare them (compare by time, the log position on the master node with the log position
on the slave's). My first approach was to use the mysqlbinlog to get the log position, in
the 'Master_Log_File'. But in the slave's the last position that the SQL thread has read
and executed is the 'Relay_Log_Pos', right?
I have to read the slave's relay log, in order to get the last position on the Master's
log executed? And compare with the master's log?

Thank you.

Regards,
Miguel Araújo