The blkhash library is up to 4 order of magnitude faster than openssl
using the same digest algorithm.
blkhash improves performance in several ways:
- Zero optimization - avoiding the work for computing a hash for unallocated ares in an image, or areas full of zeroes.
- Parallel computation - computing hashes in parallel using multiple threads.
- Asynchronous API - speeding up hashing with large number of threads and integrating well with asynchronous I/O libraries
blkhash can be up to 4 orders of magnitude faster than SHA256,
depending on the image content and number of threads.
The following graph shows zero optimization performance for 3 cases:
- data - hashing buffer full of non-zero data
- zero - hashing buffer full of zeros
- hole - hashing unallocated area
The benchmarks shown here ran on AWS c7g.metal instance with 64 cores running Ubuntu.
blkhash performance is tested using the blkhash-bench program,
measuring the throughput of the library by hashing buffers directory
into the library, without actual I/O.
The blkhash-bench program is run by the bench/run tool:
bench/run bench/blkhash.yaml
The graphs were created using the plot-blkhash.py tool from the json test results.
See blksum performance for computing a hash of actual disk images on storage.
See the test/results directory for test results and images.