unitrace reports work-group size {0; 0; 0} for OpenMP offload kernels

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Evaluación

Dificultad
3/5
Tiempo estimado
1-2 días
Aptitud para principiantes
70/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
cpp

Línea de trabajo

Start in tools/unitrace/src/levelzero/ze_collector.h at the zeKernelSetGroupSize handler and the launch-call handler shown in the issue. Trace how launch parameters are recorded, then build and run the provided OpenMP offload reproducer with unitrace. Done when the reported group size is {64; 1; 1} rather than {0; 0; 0}, and existing launch handling still works.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

unitrace reports the work-group size of every OpenMP offload kernel as {0; 0; 0}. The OpenMP runtime (libomptarget, Level Zero plugin) launches kernels with zeCommandListAppendLaunchKernelWithArguments and passes the group size in its pGroupSizes argument. It does not call zeKernelSetGroupSize. unitrace records the group size only in its handler of zeKernelSetGroupSize, so for these kernels the size stays 0.

Reproducer, built with icpx -fiopenmp -fopenmp-targets=spir64 repro.cpp -o repro:

#include <cstdio>

int main() {
  const int N = 1 << 20;
  static float a[N];
#pragma omp target teams distribute parallel for map(from : a[0 : N])
  for (int i = 0; i < N; ++i)
    a[i] = 2.0f * i;
  printf("%f\n", a[N - 1]);
  return 0;
}

unitrace -d -v ./repro reports:

"__omp_offloading_821_3df0002__Z4main_l6[SIMD32 {16384; 1; 1} {0; 0; 0}]", 1, 9760, ...

With the change below the same run reports {16384; 1; 1} {64; 1; 1}. The change passes the group size of the launch call to the existing zeKernelSetGroupSize handler:

--- a/tools/unitrace/src/levelzero/ze_collector.h
+++ b/tools/unitrace/src/levelzero/ze_collector.h
@@ -4908,6 +4908,12 @@ class ZeCollector {
     ze_instance_data.instrument_ = false;
     ze_instance_data.query_ = nullptr;
     ZeCollector* collector = reinterpret_cast<ZeCollector*>(global_data);
+    // This launch call passes the group size instead of zeKernelSetGroupSize.
+    if (params->pgroupSizes != nullptr) {
+      ze_group_size_t gs = *(params->pgroupSizes);
+      ze_kernel_set_group_size_params_t p{params->phKernel, &gs.groupSizeX, &gs.groupSizeY, &gs.groupSizeZ};
+      OnExitKernelSetGroupSize(&p, ZE_RESULT_SUCCESS, global_data, instance_data);
+    }
     if (collector->ShouldCaptureAppend(*(params->phCommandList),
                                        *(params->pnumWaitEvents),
                                        *(params->pphWaitEvents))) {
Lenguaje dominante
C++
Estrellas
278
Forks
75
Métricas de merge de PR
Sin PR fusionados en 30 d

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