[Performance] Scatter operator regression 1.20.0 → 1.21.0

[junghyunpark2001]

Describe the issue

Summary

Scatter (opset 10) shows regression on larger tensors.

Test Results

Test Case	Input Shape	Type	Kernel Change
axis1_highrank	(2,64,28,28)	float32	+16.89%
axis_minus2_midrank	(4,6,10)	float32	+10.97%
axis1_batch_2d	(8,128)	float32	+3.16%
axis2_overlap	(2,3,5)	float32	+4.07%
negative_axis_last_dim	(2,5)	float32	+0.16%

Regression Pattern

Regressed (float32):

• 4D tensors with high channel count: +16.89%
• 3D tensors: +10.97%

Stable (float32):

• 2D tensors: <5%

To reproduce

cd evaluation/report
python script_profiling.py scatter_scatter_10_scatter_axis1_highrank_float32 1.20.0 1.21.0

Archive.zip

Urgency

No response

Platform

Linux

OS Version

Ubuntu 24.04.3 LTS

ONNX Runtime Installation

Released Package

ONNX Runtime Version or Commit ID

1.21

ONNX Runtime API

Python

Architecture

X64

Execution Provider

Default CPU

Execution Provider Library Version

No response

Model File

No response

Is this a quantized model?

Yes