3 ms·

If I recompile blake2sp with "/O2" optimization, it improves to 171MB/sec. Too slow! You're doing something wrong or measuring some slow implementation :) It s

• jasode 9y ago
  >Too slow! You're doing something wrong I do now notice that my ASUS motherboard monitor software is reporting that my CPU is at 1.2GHz instead of 3.3GHz. There's probably something wrong there. However, even if I get it up to 3.3GHz, the relative speeds between different benchmarks won't change. I got the same relative numbers on the Macbook. >measuring a hand-optimized assembly version and then compared it to a C version compiled with optimization disabled? O_o Because there's lots of Wei Dai code that's C++ code instead of asm. He delivered his MSVC project with optimizations disabled instead of "/O3" so it made the most sense to start with optimizations disabled everywhere as a preliminary benchmark. If I recompile Wei Dai's code with optimization, it will make Crypto++ perform faster and make blake2sp look slower. In the end, it's a moot point because blake2sp with "/O2" is still slower than Crypto++ SHA256. >Using such large buffers will generate a lot of noise in benchmarks. Why? If you study the blake2sp source code, you'll see a loop inside the hash update() function to handle arbitrary sizees of buffers. Why does a loop outside that update() mean "less noise"? Why does adding more function calls of BUFSIZETOTAL divided by 8192 equal less noise?
  • dchest 9y ago
    If I recompile Wei Dai's code with optimization, it will make Crypto++ perform better and make blake2sp look slower. Just do it. If it's slower, you're doing something wrong. Which implementation of blake2sp are you measuring? It should be at least 1.5x as fast. Why? If you study the source code, you'll see a loop inside the hash update() function. Why does a loop outside that update() mean "less noise"? Why does adding more function calls of BUFSIZETOTAL divided by BLOCK PROCESSING SIZE equal less noise? Because you'll be measuring a lot of memory copying time apart from hashing time. Dealing with memory outside of CPU cache introduces a lot of variance. I suggest that instead of our discussion you should try to reproduce the results of https://bench.cr.yp.to https://bench.cr.yp.to (which is a highly trusted source, e.g. it was used during SHA-3 competition by NIST and participants): if something doesn't approximately match it means you did something wrong. In the process, you'll learn how to properly benchmark hash functions and make some sciency science by reproducing results! :-)
    • jasode 9y ago
      I think I found the issue. In terms of absolute (not relative) MB/sec performance, the main culprit is the slow cpu speed of 1.2GHz single threaded performance instead of 3.3GHz. The other investigations into "/O2 /O3" optimizations or 8k outer loop were red herrings. However, for relative MB/sec performance comparison to SHA256, it seems to point back to the blake2 official reference code (non SSE) being very slow. Wei Dai Crypto++ also happens to have BLAKE2 algorithm and when I executed that, it ran at 525MB/sec which was faster than SHA256 and also faster than SHA1. No outer 8k chunk loop necessary for Crypto++ benchmark. >Because you'll be measuring a lot of memory copying time apart from hashing time. Yes, I notice the numerous memcpy() functions in the blake2s?-ref.c. For additional tests, I rewrote the loop to call update() on chunks and tried various sizes (8k, 16k, 32k, ... 256k, 512k, 1MB). At 256k chunks and below, I got 235MB/sec which was an improvement but still slower than SHA256. As stated above, the real key was to use an optimized BLAKE2 algorithm instead of the official reference code. >you should try to reproduce the results of https://bench.cr.yp.to https://bench.cr.yp.to I can't tell if the blake2 entries in https://bench.cr.yp.to https://bench.cr.yp.to are using official reference or optimized code so trying to replicate those results with official reference files may be a wild goose chase.