From 743a0d8f7152e61422a94179a946cfe06ef3ca1c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Del=20Pino?= <stephane.delpino44@gmail.com>
Date: Mon, 25 Jul 2022 00:05:31 +0200
Subject: [PATCH] Change thread allocation policy for tests to avoid
oversubscription
Oversubscription can degrade parallel performances substantially
---
tests/mpi_test_main.cpp | 10 +++++++++-
tests/test_main.cpp | 8 +++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/tests/mpi_test_main.cpp b/tests/mpi_test_main.cpp
index 51b222c08..10314a4dc 100644
--- a/tests/mpi_test_main.cpp
+++ b/tests/mpi_test_main.cpp
@@ -18,12 +18,17 @@
#include <cstdlib>
#include <filesystem>
+#include <thread>
int
main(int argc, char* argv[])
{
parallel::Messenger::create(argc, argv);
- Kokkos::initialize({4, -1, -1, true});
+
+ const int nb_max_threads = std::max(std::thread::hardware_concurrency(), 1u);
+ const int nb_threads = std::max(nb_max_threads / parallel::Messenger::getInstance().size(), 1ul);
+
+ Kokkos::initialize({nb_threads, -1, -1, true});
PETScWrapper::initialize(argc, argv);
@@ -56,6 +61,9 @@ main(int argc, char* argv[])
session.useConfigData(data);
}
+ std::cout << "Using " << nb_threads << " threads per process [" << nb_threads << "x"
+ << parallel::Messenger::getInstance().size() << "]\n";
+
// Disable outputs from tested classes to the standard output
std::cout.setstate(std::ios::badbit);
diff --git a/tests/test_main.cpp b/tests/test_main.cpp
index 91d9a080a..3eff2f311 100644
--- a/tests/test_main.cpp
+++ b/tests/test_main.cpp
@@ -15,11 +15,15 @@
#include <MeshDataBaseForTests.hpp>
+#include <thread>
+
int
main(int argc, char* argv[])
{
parallel::Messenger::create(argc, argv);
- Kokkos::initialize({4, -1, -1, true});
+ const int nb_threads = std::max(std::thread::hardware_concurrency(), 1u);
+
+ Kokkos::initialize({nb_threads, -1, -1, true});
PETScWrapper::initialize(argc, argv);
SLEPcWrapper::initialize(argc, argv);
@@ -32,6 +36,8 @@ main(int argc, char* argv[])
if (config.listReporters() or config.listTags() or config.listTests()) {
result = session.run();
} else {
+ std::cout << "Using " << nb_threads << " threads\n";
+
// Disable outputs from tested classes to the standard output
std::cout.setstate(std::ios::badbit);
--
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