[SYCL][L0] Add temporary option to allow user to use copy engine for device to device copy

Author: asudarsa

sycl/plugins/level_zero/pi_level_zero.cpp

@@ -4946,6 +4946,17 @@ pi_result piEnqueueMemBufferWriteRect(
       EventWaitList, Event);
 }
 
+// This is an experimental option to test performance of device to device copy
+// operations on copy engines (versus compute engine)
+static bool UseCopyEngineForD2DCopy(bool HasCopyEngine) {
+  if (HasCopyEngine) {
+    const char *CopyEngineForD2DCopy =
+        std::getenv("SYCL_PI_LEVEL_ZERO_USE_COPY_ENGINE_FOR_D2D_COPY");
+    return (CopyEngineForD2DCopy && (std::stoi(CopyEngineForD2DCopy) != 0));
+  }
+  return false;
+}
+
 pi_result piEnqueueMemBufferCopy(pi_queue Queue, pi_mem SrcBuffer,
                                  pi_mem DstBuffer, size_t SrcOffset,
                                  size_t DstOffset, size_t Size,
@@ -4957,6 +4968,11 @@ pi_result piEnqueueMemBufferCopy(pi_queue Queue, pi_mem SrcBuffer,
   // Copy engine is preferred only for host to device transfer.
   // Device to device transfers run faster on compute engines.
   bool PreferCopyEngine = (SrcBuffer->OnHost || DstBuffer->OnHost);
+
+  // Temporary option added to use copy engine for D2D copy
+  // This is an experimental option and will be removed soon
+  PreferCopyEngine |= UseCopyEngineForD2DCopy(Queue->Device->hasCopyEngine());
+
   return enqueueMemCopyHelper(
       PI_COMMAND_TYPE_MEM_BUFFER_COPY, Queue,
       pi_cast<char *>(DstBuffer->getZeHandle()) + DstOffset,
@@ -6204,6 +6220,11 @@ pi_result piextUSMEnqueueMemcpy(pi_queue Queue, pi_bool Blocking, void *DstPtr,
   // (versus compute engine).
   bool PreferCopyEngine = !IsDevicePointer(Queue->Context, SrcPtr) ||
                           !IsDevicePointer(Queue->Context, DstPtr);
+
+  // Temporary option added to use copy engine for D2D copy
+  // This is an experimental option and will be removed soon
+  PreferCopyEngine |= UseCopyEngineForD2DCopy(Queue->Device->hasCopyEngine());
+
   return enqueueMemCopyHelper(
       // TODO: do we need a new command type for this?
       PI_COMMAND_TYPE_MEM_BUFFER_COPY, Queue, DstPtr, Blocking, Size, SrcPtr,