On Wed, Sep 18, 2013 at 10:30 AM, Lonni J Friedman <netllama@gmail.com> wrote:
> > This looks similar to cases I've seen of THP defrag going wild. > Did the OS version or configuration change? Did the PostgreSQL > memory settings (like shared_buffers) change?
I think you're onto something here with respect to THP defrag going wild. I set /sys/kernel/mm/transparent_hugepage/defrag to 'never' and immediately the load dropped on both slaves from over 5.00 to under 1.00.
So this raises the question, is this a kernel bug, or is there some other solution to the problem? Also, seems weird that the problem didn't happen until I switched from 9.2 to 9.3. Is it possible this is somehow related to the change from using SysV shared memory to using Posix shared memory and mmap for memory management?
I would guess that it is probably a kernel bug which gets efficiently exercised by the SysV to Posix change.
