Add support of HIP_HIDDEN_FREE_MEM, to deduct the returned available

memory from hipMemGetInfo API, measured in MB.

Change-Id: I7a8260c12e032e04e26611db4c38c893a29f2653

src/hip_hcc.cpp

@@ -78,6 +78,7 @@ int HIP_FORCE_P2P_HOST = 0;
 int HIP_FAIL_SOC = 0;
 int HIP_DENY_PEER_ACCESS = 0;
 
+int HIP_HIDDEN_FREE_MEM = 0;
 // Force async copies to actually use the synchronous copy interface.
 int HIP_FORCE_SYNC_COPY = 0;
 
@@ -1204,8 +1205,8 @@ void HipReadEnv()
         tokenize(HIP_LAUNCH_BLOCKING_KERNELS, ',', &g_hipLaunchBlockingKernels);
     }
     READ_ENV_I(release, HIP_API_BLOCKING, 0, "Make HIP APIs 'host-synchronous', so they block until completed.  Impacts hipMemcpyAsync, hipMemsetAsync." );
-
-
+    
+    READ_ENV_I(release, HIP_HIDDEN_FREE_MEM, 0, "Amount of memory to hide from the free memory reported by hipMemGetInfo, specified in MB. Impacts hipMemGetInfo." );
 
     READ_ENV_C(release, HIP_DB, 0,  "Print debug info.  Bitmask (HIP_DB=0xff) or flags separated by '+' (HIP_DB=api+sync+mem+copy)", HIP_DB_callback);
     if ((HIP_DB & (1<<DB_API))  && (HIP_TRACE_API == 0)) {

src/hip_hcc_internal.h

@@ -61,7 +61,7 @@ extern int HIP_FORCE_P2P_HOST;
 
 extern int HIP_COHERENT_HOST_ALLOC;
 
-
+extern int HIP_HIDDEN_FREE_MEM;
 //---
 // Chicken bits for disabling functionality to work around potential issues:
 extern int HIP_SYNC_HOST_ALLOC;

src/hip_memory.cpp

@@ -1130,6 +1130,10 @@ hipError_t hipMemGetInfo  (size_t *free, size_t *total)
             hc::am_memtracker_sizeinfo(device->_acc, &deviceMemSize, &hostMemSize, &userMemSize);
 
             *free =  device->_props.totalGlobalMem - deviceMemSize;
+
+           // Deduct the amount of memory from the free memory reported from the system
+           if(HIP_HIDDEN_FREE_MEM)
+               *free -= (size_t)HIP_HIDDEN_FREE_MEM*1024*1024;
         }
         else {
              e = hipErrorInvalidValue;