[mpich-discuss] MPICH Test Suite - limit number of processes

Max R. Dechantsreiter max at performancejones.com
Sun Jan 15 08:09:19 CST 2023

Thank you for your suggestion.

However, I did not see how to carry it through; perhaps one
day I will comb through the User's Guide.

Instead I ran 'make testing' to completion on four cores:
elapsed time was 2h36m53s on Intel(R) Xeon(R) CPU E5-2620 v4
(2.10GHz); all but two tests passed, with the two that did
not pass simply timing out (after 180s).

Then I ran it again after modifying "runtests" thus:

sed -i 's/^$ppnMax  = -1;/$ppnMax  = 4;/' $RUNTESTS
sed -i 's/^$np_max     = -1;/$np_max     = 4;/' $RUNTESTS

where RUNTESTS=~test/mpi/runtests.  (Alternatively these
variables could be modified in $RUNTESTS.in before prior to
building MPICH.)

Changing those variables limited the maximum number of
processes to 4 as desired.  The salient issues were the
warnings 'Number of processors must divide 10' that I
presume could be avoided by setting $np_max=2 or 5; the
number of tests affected was relatively small: 13 of 2524
tests failed, with no test timing out.  Elapsed time was
1h04m28s - so the savings in time was significant but not
spectacular, suggesting that relatively few tests in the
original run oversubscribed the cores available in my VPS.

On Thu, Jan 12, 2023 at 04:29:07PM +0000, Zhou, Hui wrote:
> Unfortunately, the number of processes for each test is hardcoded in the testlist files. There is no mechanism for filtering or dynamically modifying them. You could either maintain a custom patch to modify the testlist, or have a script applying a separate xfail list. An example of such xfail list that we used in our internal testing is in test/mpi/maint/jenkins/xfail.conf. If the custom patch solution won't work in your situation, please open an github issue describing your use case, and we can discuss to add a filtering option to the runtests script.
> --
> Hui
> ________________________________
> From: Max R. Dechantsreiter via discuss <discuss at mpich.org>
> Sent: Thursday, January 12, 2023 9:58 AM
> To: discuss at mpich.org <discuss at mpich.org>
> Cc: Max R. Dechantsreiter <max at performancejones.com>
> Subject: [mpich-discuss] MPICH Test Suite - limit number of processes
> I would like to limit the number of processes used by the
> MPICH Test Suite, which I run by "make testing" after
> building MPICH.
> I tried
> export MPITEST_PPNMAX=<n> # The maximum number of processes per node.
> but this had no apparent effect: some tests still ran
> using more than 4 processes, when I replaced <n> by 4.
> How could I restrict these tests to run with maximum 4
> processes, for example?
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