IMX8MP EVK / tflite Post Process execution core

[Kei-Ueda]

Hi all,

I’ve tried to use SSD Mobilenet V2 .tflite(trained/converted through Object Detection API) on IMX8MP EVK.

Here is benchmark_model result of the .tflite

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Operator-wise Profiling Info for Regular Benchmark Runs:
============================== Run Order ==============================

[node type]	[start]	[first]	[avg ms]	[%]	[cdf%]	[mem KB]	[times called]
QUANTIZE	0	0.615	0.607	2.66%	2.66%	0	1
TfLiteNnapiDelegate	0.607	18.077	17.979	78.89%	81.56%	0	1
DEQUANTIZE	18.587	0.025	0.025	0.11%	81.67%	0	1
DEQUANTIZE	18.613	0.473	0.474	2.08%	83.75%	0	1
TFLite_Detection_PostProcess	19.087	3.746	3.704	16.25%	100.00%	0	1

============================== Top by Computation Time ==============================

[node type]	[start]	[first]	[avg ms]	[%]	[cdf%]	[mem KB]	[times called]
TfLiteNnapiDelegate	0.607	18.077	17.979	78.89%	78.89%	0	1
TFLite_Detection_PostProcess	19.087	3.746	3.704	16.25%	95.15%	0	1
QUANTIZE	0	0.615	0.607	2.66%	97.81%	0	1
DEQUANTIZE	18.613	0.473	0.474	2.08%	99.89%	0	1
DEQUANTIZE	18.587	0.025	0.025	0.11%	100.00%	0	1

Number of nodes executed: 5
============================== Summary by node type ==============================

[Node type]	[count]	[avg ms]	[avg %]	[cdf %]	[mem KB]	[times called]
TfLiteNnapiDelegate	1	17.978	78.90%	78.90%	0	1
TFLite_Detection_PostProcess	1	3.704	16.26%	95.15%	0	1
QUANTIZE	1	0.606	2.66%	97.81%	0	1
DEQUANTIZE	2	0.499	2.19%	100.00%	0	2

Timings (microseconds): count=50 first=22936 curr=22800 min=22694 max=22972 avg=22789 std=58
Memory (bytes): count=0
5 nodes observed

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It seems that Post-Process are executed on not NPU(NNAPI) but CPU core.

If so, I assume this behavior differs from Processor Reference Manual which explains PPU in NPU should execute Post-Process(Non-max Suppression).

Also I can see unexpected processing delay in Post-Process on on IMX8MP EVK now.

So I need countermeasure for this behavior.

Thanks in advance.

Best Regards,

[Kei-Ueda]

Hi all,

I confirmed newest i.MX 8M Plus Applications Processor

Reference Manual Rev.1(https://www.nxp.com/webapp/Download?colCode=IMX8MPRM)

and the description of Supported Neural Network Layers list was gone.

Does this mean NPU(NNAPI) cannot support PostProcess including Non-maximum suppression currently?

Please let me know details.

Thanks in advance.

Best Regards,