On Sunday, January 31, 2021, Matthew Miller <mattdm@fedoraproject.org> wrote:
On my Intel i7 laptop, xxhash is a small but clear performance win over
crc32c:

    $ ./hash-speedtest  10000000
    Block size:     4096
    Iterations:     10000000
    Implementation: builtin

        NULL-NOP: cycles:   1372543560, c/i      137
     NULL-MEMCPY: cycles:   2844174884, c/i      284
          CRC32C: cycles:   9673117404, c/i      967
          XXHASH: cycles:   7129819594, c/i      712
          SHA256: cycles: 649914613520, c/i    64991
         BLAKE2b: cycles: 153513008046, c/i    15351


And I'm given to understand that this is even more the case on newer CPUs.

Plus, it's 64 bit instead of 32 bit. The 256-bit algorithms are obviously
much, much slower and probably not right for a default, but should we
consider making xxhash the default for Fedora Linux systems with btrfs?


Comparing the hash algorithms in isolation doesn't mean much - does it make a difference if you try various file system workloads with the different algorithms?

 
--
Matthew Miller
<mattdm@fedoraproject.org>
Fedora Project Leader
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