Fixed test failures on CPU OpenCL (#3003)

platforms/opencl/src/OpenCLContext.cpp

@@ -530,7 +530,9 @@ void OpenCLContext::initialize() {
             energyParamDerivBuffer.initialize<cl_float>(*this, numEnergyParamDerivs*energyBufferSize, "energyParamDerivBuffer");
         addAutoclearBuffer(energyParamDerivBuffer);
     }
-    int bufferBytes = max(velm.getSize()*velm.getElementSize(), energyBufferSize*energyBuffer.getElementSize());
+    int bufferBytes = max(max(velm.getSize()*velm.getElementSize(),
+            energyBufferSize*energyBuffer.getElementSize()),
+            longForceBuffer.getSize()*longForceBuffer.getElementSize());
     pinnedBuffer = new cl::Buffer(context, CL_MEM_ALLOC_HOST_PTR, bufferBytes);
     pinnedMemory = currentQueue.enqueueMapBuffer(*pinnedBuffer, CL_TRUE, CL_MAP_READ | CL_MAP_WRITE, 0, bufferBytes);
     for (int i = 0; i < numAtoms; i++) {

platforms/opencl/tests/TestOpenCLNonbondedForce.cpp

@@ -155,6 +155,8 @@ void runPlatformTests() {
     testParallelComputation(NonbondedForce::Ewald);
     testParallelComputation(NonbondedForce::PME);
     testReordering();
-    if (canRunHugeTest())
-        testHugeSystem();
+    if (canRunHugeTest()) {
+        double tol = (platform.getPropertyDefaultValue("Precision") == "single" ? 1e-4 : 1e-5);
+        testHugeSystem(tol);
+    }
 }

tests/TestNonbondedForce.h

@@ -536,7 +536,7 @@ void testLargeSystem() {
     ASSERT_EQUAL_TOL(state.getPotentialEnergy(), referenceState.getPotentialEnergy(), tol);
 }
 
-void testHugeSystem() {
+void testHugeSystem(double tol=1e-5) {
     // Create a system with over 3 million particles.
     
     const int gridSize = 150;
@@ -590,7 +590,7 @@ void testHugeSystem() {
     State state2 = context.getState(State::Energy);
     context.setPositions(positions3);
     State state3 = context.getState(State::Energy);
-    ASSERT_EQUAL_TOL(state2.getPotentialEnergy(), state3.getPotentialEnergy()+norm*delta, 1e-5)
+    ASSERT_EQUAL_TOL(state2.getPotentialEnergy(), state3.getPotentialEnergy()+norm*delta, tol)
 }
 
 void testDispersionCorrection() {