Add HIP_BLOCKING_SYNC environment var to control stream sync behavior.

[ROCm/clr commit: 6950d3f9e9]

projects/clr/hipamd/src/hip_hcc.cpp

@@ -69,6 +69,7 @@ int HIP_ATP_MARKER= 0;
 int HIP_DB= 0;
 int HIP_VISIBLE_DEVICES = 0; /* Contains a comma-separated sequence of GPU identifiers */
 int HIP_NUM_KERNELS_INFLIGHT = 128;
+int HIP_BLOCKING_SYNC = 0;
 
 
 std::once_flag hip_initialized;
@@ -177,7 +178,7 @@ void ihipStream_t::wait(LockedAccessor_StreamCrit_t &crit, bool assertQueueEmpty
 {
     if (! assertQueueEmpty) {
         tprintf (DB_SYNC, "stream %p wait for queue-empty..\n", this);
-        crit->_av.wait();
+        crit->_av.wait(HIP_BLOCKING_SYNC ? hc::hcWaitModeBlocked : hc::hcWaitModeActive);
     }
 
     crit->_kernelCnt = 0;
@@ -257,8 +258,8 @@ void ihipStream_t::lockclose_postKernelCommand(hc::accelerator_view *av)
 {
 
     if (HIP_LAUNCH_BLOCKING) {
-        // TODO - fix this so it goes through proper stream::wait() call.
-        av->wait();  // direct wait OK since we know the stream is locked. 
+        // TODO - fix this so it goes through proper stream::wait() call.// direct wait OK since we know the stream is locked. 
+        av->wait(hc::hcWaitModeActive);  
         tprintf(DB_SYNC, " %s LAUNCH_BLOCKING for kernel completion\n", ToString(this).c_str());
     }
 
@@ -1008,7 +1009,9 @@ void ihipInit()
     READ_ENV_I(release, HIP_VISIBLE_DEVICES, CUDA_VISIBLE_DEVICES, "Only devices whose index is present in the secquence are visible to HIP applications and they are enumerated in the order of secquence" );
 
 
-    READ_ENV_I(release, HIP_NUM_KERNELS_INFLIGHT, 128, "Number of kernels per stream ");
+    READ_ENV_I(release, HIP_BLOCKING_SYNC, 0, "Use blocking synchronization for stream waits.  This may increase latency but is friendlier to other processes. If 0, spin-wait.");
+
+    READ_ENV_I(release, HIP_NUM_KERNELS_INFLIGHT, 128, "Max number of inflight kernels per stream before active synchronization is forced.");
 
     // Some flags have both compile-time and runtime flags - generate a warning if user enables the runtime flag but the compile-time flag is disabled.
     if (HIP_DB && !COMPILE_HIP_DB) {