Why does the pyfhel library run dozens of times faster than the seal library?

[Lionhehao]

I first wrote a code for dense state matrix multiplication based on the seal library. After transplanting it to the pyfhel library, I found that the speed was much faster. So I tested the ciphertext multiplication of ckks locally.

Without performing re-linearization, the time consumption of 1000 multiplications was:
seal 48s c++
pyfhel 1s python

This makes me feel unbelievable. My cpu is i3-10100f. Does pyfhel use gpu acceleration?

[ShokofehVS]

Based on previous questions and answers regarding the GPU support in Pyfhel, you can refer to these issues: #205, #171. All in all, Pyfhel depends on the underlying backend FHE libs, which have not yet been ported to GPU.

[ibarrond]

@Lionhehao I suspect two things migth be in play:

• The multiplication in Pyfhel might be using parallelisation across several CPUs.
• The multiplication happens in-place in Pyfhel, if you are running many multiplications in SEAL creating new objects every time you might be paying some extra computational cost.