Reduce accuracy test default host memory limit

Author: eng-flavio-teixeira

clients/tests/gtest_main.cpp

@@ -339,7 +339,9 @@ int main(int argc, char* argv[])
          "Logical size of input buffer.")
         ("osize", po::value<std::vector<size_t>>(&manual_params.osize)->multitoken(),
          "Logical size of output.")
-        ("R", po::value<size_t>(&ramgb)->default_value((start_memory.total_bytes + ONE_GiB - 1) / ONE_GiB), "Ram limit in GiB for tests.")
+        ("R", po::value<size_t>(&ramgb)->default_value((static_cast<size_t>(start_memory.total_bytes * system_memory::percentage_usable_memory)
+             + ONE_GiB - 1)
+            / ONE_GiB), "Ram limit in GiB for tests.")
         ("V", po::value<size_t>(&vramgb)->default_value(0), "vram limit in GiB for tests.")
         ("half_epsilon",  po::value<double>(&half_epsilon)->default_value(9.77e-4))
         ("single_epsilon",  po::value<double>(&single_epsilon)->default_value(3.75e-5))

shared/accuracy_test.h

@@ -70,6 +70,13 @@ struct system_memory
 {
     size_t total_bytes = 0;
     size_t free_bytes  = 0;
+    // Limits the amount of memory used throught the tests.
+    // Test RAM limit is: total_bytes * percentage_usable_memory.
+    // If the test system has little swap space (or there are many
+    // other processes running concurrently) and we are too
+    // aggressive with host memory usage, then the test process
+    // may get OOM killed.
+    static constexpr double percentage_usable_memory = .85;
 };
 extern system_memory start_memory;