Re: [LTP] [PATCH 3/5] mm/oom0[3|4]: added 'OOM for CPUSET' and updated 'OOM with MEMCG & numa'

Jan Stancek
2013-03-15T16:06:43Z

> From: "Zhouping Liu" <zliu@redhat.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: "LTP List" <ltp-list@lists.sourceforge.net>
> Sent: Friday, 15 March, 2013 4:41:29 PM
> Subject: Re: [LTP] [PATCH 3/5] mm/oom0[3|4]: added 'OOM for CPUSET' and updated 'OOM with MEMCG & numa'
>
>
>
> ----- Original Message -----
> > From: "Jan Stancek" <jstancek@redhat.com>
> > To: "Zhouping Liu" <zliu@redhat.com>
> > Cc: "LTP List" <ltp-list@lists.sourceforge.net>
> > Sent: Friday, March 15, 2013 5:11:57 PM
> > Subject: Re: [LTP] [PATCH 3/5] mm/oom0[3|4]: added 'OOM for CPUSET'
> > and updated 'OOM with MEMCG & numa'
> >
> >
> >
> > ----- Original Message -----
> > > From: "Zhouping Liu" <zliu@redhat.com>
> > > To: "Jan Stancek" <jstancek@redhat.com>
> > > Cc: chrubis@suse.cz, "LTP List" <ltp-list@lists.sourceforge.net>
> > > Sent: Friday, 15 March, 2013 3:52:26 AM
> > > Subject: Re: [LTP] [PATCH 3/5] mm/oom0[3|4]: added 'OOM for
> > > CPUSET'
> > > and updated 'OOM with MEMCG & numa'
> >
> > > > We could add a simple function to numa_helper, but I'm not sure
> > > > what
> > > > it would return as default, some tests care about nodes with
> > > > memory.
> > >
> > > yes, what you care about is right, but now we only need a
> > > function,
> > > which
> > > can tell us the system have more than one node, we don't care
> > > about
> > > the
> > > nodes have
> > > CPUs or memory.
> >
> > What I was wondering is why that comment said "rough estimate",
>
> because in the old version, I just used the max node id to judge a
> NUMA system,
> which maybe is not strict.
>
> > it looks quite accurate. Anyway, thanks for clarifying.
>
> in the V2 version, I removed the ISNUMA variable, and added a new
> function is_numa(),
> inside the function, the system, which has 1 more than numa node, and
> each node at
> least contains memory, is regarded as a numa system. I think it's
> more reasoned,
> because NUMA is mainly about memory, more case will fail if the node
> has no memory.
> do you agree?

I agree. Some failures on unbalanced NUMA systems led to introducing that check.
I was looking at our system pool and number of such systems is very low,
so I don't think we are loosing very much by requiring 2+ nodes with memory.

>
> --
> Thanks,
> Zhouping