I heard from various sources (mostly from the official documents) that Tensorflow Lite (for ARM) uses these three libraries - Ruy, Eigen, XNNPACK - for its operation.
I understand they somehow accelerate the computation (mainly convolution) in TF Lite, but I'm not exactly sure what purpose each library serves. I know Eigen is a BLAS library, but I'm not sure what others are and how they are related to each other in TF Lite.
Would someone care to explain what different purposes they serve and how they are used in conjunction in TF Lite? (Call Stacks maybe?)
I've been looking around the official documentations of each libraries but I was unable to find much details for Ruy and XNNPACK. Ruy says that it provides efficient matrix multiplication, but isn't that what BLAS libraries do?
Older version of TensorFlow Lite used Eigen and Gemmlowp library to accelerate the computation. However on Arm platforms the performance was worst compared to e.g. Arm Compute Library.
TensorFlow Lite replaced the Eigen and Gemmlowp around version 2.3 and with Ruy matrix multiplication library. They serves similar purpose, but Ruy performs better. The Ruy is default on Arm platform, but you can still compile the TensorFlow Lite without use of Ruy.
XNNPACK outperforms Ruy even more, but it focus solely on operation on float.
Regarding Ruy performance benchmarks check this thread https://github.com/google/ruy/issues/195, and the benchmarks on Pixel4 https://docs.google.com/spreadsheets/d/1CB4gsI7pujNRAf5Iz5vuD783QQqO2zOu8up9IpTKdlU/edit#gid=510573209.