Fix regression caused by mws in ActivationLayer

- Regression is caused by the small default mws in ActivationLayer
- Syncronization of threads takes longer than the workload on small sized tensors.
- Size 1536 is chosen arbitrarily based on the size of tensors in benchmarked networks

Resolves: [COMPMID-5655]
Signed-off-by: Mohammed Suhail Munshi <MohammedSuhail.Munshi@arm.com>
Change-Id: I02e865b578399e75484f471e67806dd4cf7502c0
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/c/VisualCompute/ComputeLibrary/+/468454
Comments-Addressed: bsgcomp <bsgcomp@arm.com>
Tested-by: bsgcomp <bsgcomp@arm.com>
Reviewed-by: Jakub Sujak <jakub.sujak@arm.com>
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/8615
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/cpu/kernels/CpuActivationKernel.cpp b/src/cpu/kernels/CpuActivationKernel.cpp
index c7e1075bfd..04a9731f4a 100644
--- a/src/cpu/kernels/CpuActivationKernel.cpp
+++ b/src/cpu/kernels/CpuActivationKernel.cpp
@@ -233,7 +233,13 @@ size_t CpuActivationKernel::get_mws(const CPUInfo &platform, size_t thread_count
     ARM_COMPUTE_UNUSED(thread_count);
     ARM_COMPUTE_UNUSED(platform);
 
-    return ICPPKernel::default_mws;
+    if(_split_dimension == Window::DimX)
+    {
+        // Don't split the work load too small if the tensor has been reinterpreted as 1D.
+        // This number is loosely chosen as threading overhead in each platform varies wildly.
+        return 1536;
+    }
+    return default_mws;
 }
 
 void CpuActivationKernel::run_op(ITensorPack &tensors, const Window &window, const ThreadInfo &info)