[Openmp-commits] [openmp] [OpenMP][libomptarget] Use two SDMA engines (PR #73633)

[via Openmp-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Jan Patrick Lehr (jplehr)

<details>
<summary>Changes</summary>

Limit the use to two SDMA engines to resolve issues with certain cards.

---
Full diff: https://github.com/llvm/llvm-project/pull/73633.diff


1 Files Affected:

- (modified) openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp (+2-2) 


``````````diff
diff --git a/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp b/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
index 208cce90d8e9277..b3eed60d2879d48 100644
--- a/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
+++ b/openmp/libomptarget/plugins-nextgen/amdgpu/src/rtl.cpp
@@ -161,8 +161,8 @@ Error asyncMemCopy(bool UseMultipleSdmaEngines, void *Dst, hsa_agent_t DstAgent,
       Dst, DstAgent, Src, SrcAgent, Size, NumDepSignals, DepSignals,
       CompletionSignal, (hsa_amd_sdma_engine_id_t)LocalSdmaEngine,
       /*force_copy_on_sdma=*/true);
-  // Increment to use one of three SDMA engines: 0x1, 0x2, 0x4
-  LocalSdmaEngine = (LocalSdmaEngine << 1) % 7;
+  // Increment to use one of two SDMA engines: 0x1, 0x2
+  LocalSdmaEngine = (LocalSdmaEngine << 1) % 3;
   SdmaEngine.store(LocalSdmaEngine, std::memory_order_relaxed);
 
   return Plugin::check(S, "Error in hsa_amd_memory_async_copy_on_engine: %s");

``````````

</details>


https://github.com/llvm/llvm-project/pull/73633