On Tue, Feb 2, 2016 at 7:34 PM, Gordon Messmer <gordon.messmer at gmail.com> wrote: > 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"? Yeah. It'd nice to see the output from top so we can see what is consuming most of the cpu or anything consuming less than it should because it's waiting for something else that's slower. It might be useful to see 'perf top' if perf is installed, and if not install it, reproduce the problem and let perf top run for a minute, then post it on fpaste or pastebin so the formatting stays semisane. -- Chris Murphy