MySQL uses half cores of my server

Question

I'm running MySQL 5.1.62 on a 64-bits Gentoo Box.

This MySQL is heavy loaded but the problem is that it uses only half the cores of the server :

Cpu0 : 84.0%us, 13.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 3.0%si, 0.0%st

Cpu1 : 62.4%us, 34.7%sy, 0.0%ni, 3.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu2 : 68.3%us, 26.7%sy, 0.0%ni, 5.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu3 : 72.3%us, 3.0%sy, 0.0%ni, 22.8%id, 2.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu4 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu5 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu6 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Cpu7 : 0.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

This is a Dual-Quad core server with : Intel(R) Xeon(R) CPU E5606 @ 2.13GHz

Any idea how to use all cores?

Thanks for your help;

Gaëtan

Answer 1

Newer versions of MySQL or the Percona enhanced MySQL server may make better use of your cores. It's fairly common for database servers to be IO bound, though.

Answer 2

Idea? Yep, but you won't like it.

Many cores do not automagically make a system faster: The workload it runs need to be easily parallelizable.

What I suspect to happen in your case is, that you are running a small number of concurrent queries, each being CPU intensive. As it happens, each will only use a single core.

To check, if this is the culprit, manually start 8 concurrent, CPU-Intensive queries - your CPUs should be fully used.