Re: -mm numa perf regression

Andrew Morton
2006-09-11T16:35:49Z

On Mon, 11 Sep 2006 15:19:01 +0100
Andy Whitcroft <apw@shadowen.org> wrote:

> Christoph Lameter wrote:
> > On Fri, 8 Sep 2006, Andy Whitcroft wrote:
> >
> >>> I have not heard back from you on this issue. It would be good to have
> >>> some more data on this one.
> >> Sorry I submitted the tests and the results filtered out to TKO, and
> >> then I forgot to check them. Looking at the graph backing this out has
> >> had no effect. As I think we'd expect from what comes below.
> >>
> >> What next?
> >
> > Get me the promised data? /proc/zoneinfo before and after the run.
> > /proc/meminfo and /sys/devices/system/node/node*/* would be helpful.
>
> Sorry for the delay, the relevant files wern't all being preserved.
> Fixed that up and reran things. The results you asked for are available
> here:
>
> http://www.shadowen.org/~apw/public/debug-moe-perf/47138/
>
> Just having a quick look at the results, it seems that they are saying
> that all of our cpu's are in node 0 which isn't right at all. The
> machine has 4 processors per node.
>
> I am sure that would account for the performance loss. Now as to why ...
>
> > Is there a way to remotely access the box?
>
> Sadly no ... I do have direct access to test on the box but am not able
> to export it.
>
> I've also started a bisection looking for it. Though that will be some
> time yet as I've only just dropped the cleaver for the first time.
>

I've added linux-mm. Can we please keep it on-list. I have a vague suspicion
that your bisection will end up pointing at one Mel Gorman. Or someone else.
But whoever it is will end up wondering wtf is going on.

I don't understand what you mean by "all of our cpu's are in node 0"?
http://www.shadowen.org/~apw/public/debug-moe-perf/47138/sys/devices/system/node.after/node0/
and
http://www.shadowen.org/~apw/public/debug-moe-perf/47138/sys/devices/system/node.before/node0/
look the same.. It depends what "before" and "after" mean, I guess...

Do we have full dmesg output for both 2.6.18-rc6-mm1 and 2.6.18-rc6?

Thanks.