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Re: ndbmtd not using all CPUs
Posted by: Mikael Ronström
Date: April 14, 2016 05:27PM

ndbmtd has a number of different thread types.
ldm threads uses the most CPU
tc, recv uses less CPU
send uses a fair amount of CPUs.

I don't know exactly what you did so it is hard to comment
more clearly.

The aim in ndbmtd is to make sure that the ldm threads are kept
busy. The other threads usually run between 30-70% loaded when
ldm threads reach around 90-95% load.

Why you get 100%, 200% and 350% I don't really know since there
is very little description of what you actually did.

Usually when I run benchmarks with MySQL Cluster like sysbench then
most of the CPU usage is in the mysqld process. A single thread
usually gives around 50% on mysqld and ndbtmd. Then as more threads
are added mysqld grows CPU usage fairly linearly whereas ndbmtd
becomes more and more effective as CPU usage goes up.

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