numa involved in instability and swap usage despite RAM free?

[Steve Kargl]

On Tue, Jun 26, 2018 at 02:39:27PM -0700, Adrian Chadd wrote:
> On Mon, 25 Jun 2018 at 11:23, Steve Kargl
> <sgk at troutmask.apl.washington.edu> wrote:
> >
> > On Sun, Jun 24, 2018 at 12:03:29PM +0200, Alexander Leidinger wrote:
> > >
> > > I don't have hard evidence, but there is enough "smell" to open up a
> > > discussion...
> > >
> > > Short:
> > > Can it be that enabling numa in the kernel is the reason why some
> > > people see instability with zfs and usage of swap while a lot of free
> > > RAM is available?
> >
> > Interesting observation.  I do have NUMA in my kernel, and swap
> > seems to be used instead of recycling freeing inactive memory.
> > Top shows
> >
> > Mem: 506M Active, 27G Inact, 98M Laundry, 2735M Wired, 1474M Buf, 1536M Free
> > Swap: 16G Total, 120M Used, 16G Free
> >
> > Perhaps, I don't understand what is meant by inactive memory.  I
> > thought that this means memory is still available in the buffer
> > cache, but nothing is current using what is there.
> >
> 
> Aren't there now per-domain VM counters you can query via sysctl?
> Maybe they'd help in diagnosing what's going on.
> 

I upgraded to a r335642 yesterday.  I haven't seen the swapping
problem, yet; although I've tried to force it.  There are 158
sysctl knobs that contain the string "vm".  Do you have a pointer
any particular one to monitor?

-- 
Steve