[CentOS] Measuring memory bandwidth utilization

On 02/02/2016 05:34 PM, Benjamin Smith wrote:
> We've ruled out IOPs for the disks (~ 20%)

How did you measure that?  What filesystem are you using?  What is the 
disk / array configuration?
Which database?

If you run "iostat -x 2" what does a representative summary look like?

>   and raw CPU load (top shows perhaps
> 1/2 of cores busy, but the system slows to a crawl.

Define "busy"?