Allow disabling scratch reclaim.

Debug and RCCL NPI assist feature.

Change-Id: I2cb76f0a086fa341465df3ede26965ab713bc3b4

runtime/hsa-runtime/core/runtime/amd_gpu_agent.cpp

@@ -963,6 +963,7 @@ void GpuAgent::AcquireQueueScratch(ScratchInfo& scratch) {
   bool large = (scratch.size > single_limit) ||
       (scratch_pool_.size() - scratch_pool_.remaining() + scratch.size > small_limit);
   large = (isa_->GetMajorVersion() < 8) ? false : large;
+  large = core::Runtime::runtime_singleton_->flag().no_scratch_reclaim() ? false : large;
   if (large)
     scratch.queue_base = scratch_pool_.alloc_high(scratch.size);
   else

runtime/hsa-runtime/core/util/flag.h

@@ -106,6 +106,9 @@ class Flag {
 
     var = os::GetEnvVar("HSA_FORCE_FINE_GRAIN_PCIE");
     fine_grain_pcie_ = (var == "1") ? true : false;
+
+    var = os::GetEnvVar("HSA_NO_SCRATCH_RECLAIM");
+    no_scratch_reclaim_ = (var == "1") ? true : false;
   }
 
   bool check_flat_scratch() const { return check_flat_scratch_; }
@@ -130,6 +133,8 @@ class Flag {
 
   bool fine_grain_pcie() const { return fine_grain_pcie_; }
 
+  bool no_scratch_reclaim() const { return no_scratch_reclaim_; }
+
   std::string enable_sdma() const { return enable_sdma_; }
 
   std::string visible_gpus() const { return visible_gpus_; }
@@ -152,6 +157,7 @@ class Flag {
   bool disable_fragment_alloc_;
   bool rev_copy_dir_;
   bool fine_grain_pcie_;
+  bool no_scratch_reclaim_;
 
   std::string enable_sdma_;