Findings

writeup: https://hackmd.io/@ceno-zkvm/Hy0Vz8bMxl

1. Sumcheck

Simple fact (or main issue that we have): adding one variable alone will take 805 cycles!!

To see how many cycles it takes to verify a sumcheck proof with nv = 2, degree = 3, you can run the cmd

cargo test --release --features "bench-metrics" --lib test_simple_sumcheck -- --nocapture

1.1 Transcript

1. To observe 3 extension elements(equivalent to 12 felts), it takes around 230 cycles. 230 is larger than 9*12 because of the overhead in processing "2-dimensional loop" / "ext2felts conversion". (issue 1)

2. observe() takes 6 or 9 cycles.
   a. if inputs.len() = 7, it will need 9 cycles;
   b. otherwise, it will need 6 cycles.

3. sample_ext: takes 62 cycles (62 = 43 + 19) where
   a. it called DuplexChallengerVariable.sample() by 4 times.
   b. it called ext_from_base_slice() by 1 time which takes 43 cycles. (issue 2)

1.2 Interpolation

issue 3

2. Solution

https://hackmd.io/@ceno-zkvm/Hy0Vz8bMxl#2-Solutions