Show HN: Krep a High-Performance String Search Utility Written in C

You can read my blog post about the project at https://dev.to/daviducolo/introducing-krep-building-a-high-p...

Hi David.

    $ (for x in `seq 1 100000`; do echo 'I am a Test Vector HeLlO World '"$x"; done) > /dev/shm/krep_tmp

Best of three runs shown:

    $ time ./krep -i hello /dev/shm/krep_tmp
    Found 43721 matches
    Search completed in 0.0017 seconds (2017.44 MB/s)
    Search details:
      - File size: 3.52 MB
      - Pattern length: 5 characters
      - Using AVX2 acceleration
      - Case-insensitive search
    real        0m0,005s
    user        0m0,001s
    sys         0m0,004s
    $ time ./krep HeLlO /dev/shm/krep_tmp
    Found 82355 matches
    Search completed in 0.0014 seconds (1259.72 MB/s)
    Search details:
      - File size: 1.71 MB
      - Pattern length: 5 characters
      - Using AVX2 acceleration
      - Case-sensitive search
    real        0m0,004s
    user        0m0,003s
    sys         0m0,004s
    $ time ./krep -i "HeLlO World" /dev/shm/krep_tmp
    Found 99958 matches
    Search completed in 0.0021 seconds (1700.54 MB/s)
    Search details:
      - File size: 3.52 MB
      - Pattern length: 11 characters
      - Using AVX2 acceleration
      - Case-insensitive search
    real        0m0,005s
    user        0m0,002s
    sys         0m0,004s
    $ time ./krep "I am a Test Vector HeLlO World" /dev/shm/krep_tmp
    Found 3964 matches
    Search completed in 0.0149 seconds (235.83 MB/s)
    Search details:
      - File size: 3.52 MB
      - Pattern length: 30 characters
      - Using AVX2 acceleration
      - Case-sensitive search
    real        0m0,016s
    user        0m0,015s
    sys         0m0,001s
    $ time ./krep -i "I am a Test Vector hello World" /dev/shm/krep_tmp
    Found 3964 matches
    Search completed in 0.0178 seconds (197.70 MB/s)
    Search details:
      - File size: 3.52 MB
      - Pattern length: 30 characters
      - Using AVX2 acceleration
      - Case-insensitive search
    real        0m0,021s
    user        0m0,017s
    sys         0m0,004s

Benchmark with fgrep (the first run was good enough):

    $ time fgrep -ci hello /dev/shm/krep_tmp
    100000
    real        0m0,003s
    user        0m0,003s
    sys         0m0,000s
    $ time fgrep -ci "I am a Test Vector hello World" /dev/shm/krep_tmp
    100000
    real 0m0,010s
    user 0m0,009s
    sys         0m0,000s
    $ time fgrep -c "I am a Test Vector HeLlO World" /dev/shm/krep_tmp
    100000
    real 0m0,005s
    user 0m0,004s
    sys         0m0,001s

This is a model name: Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz. There's 40gb of ram free and 10 cores doing nothing. shell is cpuset. On commit 95ed1853b561396c8a8bcbbdd115ed6273848e3f (HEAD -> main, origin/main, origin/HEAD). gcc is 13.3.0-6ubuntu2~24.04

tl;dr: krep produces obviously wrong results slower than fgrep.