kfdtest: Reduce libdrm VRAM usage in eviction tests

This reduces thrashing due to graphics submissions only and
significantly speeds up the BasicTest when keeping idle compute
processes evicted. In the BasicTest  compute is always idle, so
only one compute eviction and no restore is triggered. Then
graphics submissions complete quickly without thrashing each other.

Change-Id: Iae6da98903b20424a5097f235e1d09cf13e4b41b
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>

tests/kfdtest/src/KFDEvictTest.cpp

@@ -334,7 +334,7 @@ TEST_F(KFDEvictTest, BasicTest) {
     ASSERT_GE(defaultGPUNode, 0) << "failed to get default GPU Node";
     HSAuint64 vramBufSize = ALLOCATE_BUF_SIZE_MB * 1024 * 1024;
 
-    HSAuint64 vramSize = GetVramSize(defaultGPUNode);
+    HSAuint64 vramSize = GetVramSize(defaultGPUNode) * 7 / 8;
 
     if (!vramSize) {
         LOG() << "Skipping test: No VRAM found." << std::endl;
@@ -344,7 +344,7 @@ TEST_F(KFDEvictTest, BasicTest) {
     }
 
     // Use 7/8 of VRAM between all processes
-    HSAuint32 count = vramSize * 7 / (8* vramBufSize * N_PROCESSES);
+    HSAuint32 count = vramSize  / (vramBufSize * N_PROCESSES);
 
     LOG() << "Found System RAM of " << std::dec << (GetSysMemSize() >> 20) << "MB" << std::endl;
 
@@ -537,7 +537,7 @@ TEST_F(KFDEvictTest, QueueTest) {
     }
 
     HSAuint32 i;
-    HSAuint64 vramSize = GetVramSize(defaultGPUNode);
+    HSAuint64 vramSize = GetVramSize(defaultGPUNode) * 7 / 8;
 
     if (!vramSize) {
         LOG() << "Skipping test: No VRAM found." << std::endl;
@@ -547,7 +547,7 @@ TEST_F(KFDEvictTest, QueueTest) {
     }
 
     // Use 7/8 of VRAM between all processes
-    HSAuint32 count = vramSize * 7 / (8 * vramBufSize * N_PROCESSES);
+    HSAuint32 count = vramSize / (vramBufSize * N_PROCESSES);
 
     LOG() << "Found System RAM of " << std::dec << (GetSysMemSize() >> 20) << "MB" << std::endl;
 
@@ -646,7 +646,7 @@ TEST_F(KFDEvictTest, BurstyTest) {
     ASSERT_GE(defaultGPUNode, 0) << "failed to get default GPU Node";
     HSAuint64 vramBufSize = ALLOCATE_BUF_SIZE_MB * 1024 * 1024;
 
-    HSAuint64 vramSize = GetVramSize(defaultGPUNode);
+    HSAuint64 vramSize = GetVramSize(defaultGPUNode) * 7 / 8;
 
     if (!vramSize) {
         LOG() << "Skipping test: No VRAM found." << std::endl;
@@ -656,7 +656,7 @@ TEST_F(KFDEvictTest, BurstyTest) {
     }
 
     // Use 7/8 of VRAM between all processes
-    HSAuint32 count = vramSize * 7 / (8* vramBufSize * N_PROCESSES);
+    HSAuint32 count = vramSize / (vramBufSize * N_PROCESSES);
 
     LOG() << "Found System RAM of " << std::dec << (GetSysMemSize() >> 20) << "MB" << std::endl;