Performance decreases of single fuzzing process when the number of fuzzing process increases.

[datadancer]

Thanks for your excellent work.

Your optimization method could make the performance linear increase with the number of fuzzing process. It's great.

I encounter the problem of performance decrease of single fuzzing process when the number of fuzzing process increases.

I implement the In-memory log and DualFS optimization methods on libfuzzer according to your paper. When I test the fuzzing performance with multiple processes, single fuzzer performance decreases.

For example, the single process performance of libpng project fuzzer is 12032 exec/s with one process, while 4093 exec/s with 64 processes. Even 4092x64 is also much bigger than 12032, it is much smaller than 12032x64.

Have you encounter the problem of performance decrease of single fuzzing process when the number of fuzzing process increases? Can you give me some suggestions? Thanks a lot.

Environment set up:
CPU: Intel Xeon Gold 6234 * 2
Memory: 256GB DDR4
OS: Ubuntu 18.04