Re: [PATCH v2 0/4] Mitigate inconsistent NUMA imbalance behaviour

Mel Gorman
2022-05-31T14:10:10Z

On Tue, May 31, 2022 at 12:26:51PM +0200, Vincent Guittot wrote:
> > # cd work/log
> > # ../../compare-kernels.sh
> >
> > nas-mpich-mg NAS Time
> > test
> > mgD-many
> > Min mg.D 95.80 ( 0.00%)
> > Amean mg.D 110.77 ( 0.00%)
> > Stddev mg.D 21.55 ( 0.00%)
> > CoeffVar mg.D 19.46 ( 0.00%)
> > Max mg.D 155.35 ( 0.00%)
> > BAmean-50 mg.D 96.05 ( 0.00%)
> > BAmean-95 mg.D 107.83 ( 0.00%)
> > BAmean-99 mg.D 109.23 ( 0.00%)
> >
> > Note the min of 95.80 seconds, max of 155.35 and high stddev indicating
> > the results are not stable.
> >
> > The generated config is for openSUSE so it may not work for you. After
> > installing the mpich package, you'll need to adjust these lines
> >
> > export NAS_MPICH_PATH=/usr/$MMTESTS_LIBDIR/mpi/gcc/$NAS_MPICH_VERSION/bin
> > export NAS_MPICH_LIBPATH=/usr/$MMTESTS_LIBDIR/mpi/gcc/$NAS_MPICH_VERSION/$MMTESTS_LIBDIR
> >
> > NAS_MPICH_PATH and NAS_MPICH_LIBPATH need to point to the bin and lib
> > path for the mpich package your distribution ships.
>
> I have been able to run your tests on my setup: aarch64 2 nodes * 28
> cores * 4 threads. But I can't reproduce the problem, results stay
> stable before and after reverting c6f886546cb8.
>

It's unfortunate but not surprising that it's not perfectly reproducible
given that I expect this to be a race of some description and not all
machines will observe the problem.

Thanks for trying.

--
Mel Gorman
SUSE Labs