From 11e2862e5c03694a2d62ddeae8710d24e662e095 Mon Sep 17 00:00:00 2001
From: Patrick Kreissl <patrick.kreissl@pa-le.de>
Date: Mon, 3 Aug 2020 19:29:59 +0200
Subject: [PATCH] Make lb_pressure_tensor_acf test faster.

---
 testsuite/python/CMakeLists.txt            |  2 +-
 testsuite/python/lb_pressure_tensor_acf.py | 13 +++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/testsuite/python/CMakeLists.txt b/testsuite/python/CMakeLists.txt
index febd1db3ded..b94e8bb6f89 100644
--- a/testsuite/python/CMakeLists.txt
+++ b/testsuite/python/CMakeLists.txt
@@ -123,7 +123,7 @@ python_test(FILE widom_insertion.py MAX_NUM_PROC 1)
 python_test(FILE constant_pH.py MAX_NUM_PROC 4)
 python_test(FILE writevtf.py MAX_NUM_PROC 4)
 python_test(FILE lb_stokes_sphere.py MAX_NUM_PROC 4 LABELS gpu long)
-python_test(FILE lb_pressure_tensor_acf.py MAX_NUM_PROC 4 LABELS gpu long)
+python_test(FILE lb_pressure_tensor_acf.py MAX_NUM_PROC 1 LABELS gpu long)
 python_test(FILE ek_fluctuations.py MAX_NUM_PROC 1 LABELS gpu)
 python_test(FILE ek_charged_plate.py MAX_NUM_PROC 1 LABELS gpu)
 python_test(FILE ek_eof_one_species_x.py MAX_NUM_PROC 1 LABELS gpu)
diff --git a/testsuite/python/lb_pressure_tensor_acf.py b/testsuite/python/lb_pressure_tensor_acf.py
index ecda879c512..86918ab10b4 100644
--- a/testsuite/python/lb_pressure_tensor_acf.py
+++ b/testsuite/python/lb_pressure_tensor_acf.py
@@ -58,20 +58,19 @@ def test(self):
         system.integrator.run(500)
 
         # sampling
-        steps = 50000
-        p_global = np.zeros((steps, 3, 3))
-        p_node = np.zeros((steps, 3, 3))
+        p_global = np.zeros((self.steps, 3, 3))
+        p_node = np.zeros((self.steps, 3, 3))
 
         node = lb[0, 0, 0]
 
-        for i in range(steps):
+        for i in range(self.steps):
             p_node[i] = node.pressure_tensor
             p_global[i] = lb.pressure_tensor
 
             system.integrator.run(2)
 
         # Test that <sigma_[i!=j]> ~=0 and sigma_[ij]=sigma_[ji]
-        tol_global = 4 / np.sqrt(steps)
+        tol_global = 4 / np.sqrt(self.steps)
         tol_node = tol_global * np.sqrt(N_CELLS**3)
 
         # check single node
@@ -101,7 +100,7 @@ def test(self):
                 # Calculate acf
                 tmp = np.correlate(
                     p_global[:, i, j], p_global[:, i, j], mode="full")
-                acf = tmp[len(tmp) // 2:] / steps
+                acf = tmp[len(tmp) // 2:] / self.steps
 
                 # integrate first part numerically, fit exponential to tail
                 t_max_fit = 50 * TAU
@@ -132,6 +131,7 @@ class TestLBPressureACFCPU(TestLBPressureACF, ut.TestCase):
 
     def setUp(self):
         self.lb_class = espressomd.lb.LBFluid
+        self.steps = 4000
 
 
 @utx.skipIfMissingGPU()
@@ -139,6 +139,7 @@ class TestLBPressureACFGPU(TestLBPressureACF, ut.TestCase):
 
     def setUp(self):
         self.lb_class = espressomd.lb.LBFluidGPU
+        self.steps = 15000
 
 
 if __name__ == "__main__":