3 ms·
That's measuring 'cksum', which must have an awfully slow implementation. The document notes that this is distinct from measuring PG's checksum performance. (
by loeg 2y ago
That's measuring 'cksum', which must have an awfully slow implementation. The document notes that this is distinct from measuring PG's checksum performance. (I think it's a pretty useless measurement.)
Earlier (page 4):
> How much CPU time does it take to checksum...
> ...a specific amount of data? This is easy to estimate because PostgreSQL uses the crc32 algorithm which is very simple, and (GNU) Linux has a command line program that does the same thing: cksum.
Yeah, using cksum as an estimate here appears to be very flawed.
- Joe_Cool 2y agoThat is weird. Seems like crc optimization is quite a rabbit hole. https://github.com/komrad36/CRC https://github.com/komrad36/CRC has a massive section about it in the README. Really interesting.
- loeg 2y agoYeah. crc32 may be simple in theory, but doing it as fast as possible utilizing the various execution units of modern hardware is challenging.