On Wed, Nov 23, 2022 at 4:58 AM David Rowley <dgrowle...@gmail.com> wrote:
> My current thoughts are that it might be best to go with 0005 to start > with. +1 > I know Melanie is working on making some changes in this area, > so perhaps it's best to leave 0002 until that work is complete. There seem to be some open questions about that one as well. I reran the same test in [1] (except I don't have the ability to lock clock speed or affect huge pages) on an older CPU from 2014 (Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz, kernel 3.10 gcc 4.8) with good results: HEAD: Testing a1 latency average = 965.462 ms Testing a2 latency average = 1054.608 ms Testing a3 latency average = 1078.263 ms Testing a4 latency average = 1120.933 ms Testing a5 latency average = 1162.753 ms Testing a6 latency average = 1298.876 ms Testing a7 latency average = 1228.775 ms Testing a8 latency average = 1293.535 ms 0001+0005: Testing a1 latency average = 791.224 ms Testing a2 latency average = 876.421 ms Testing a3 latency average = 911.039 ms Testing a4 latency average = 981.693 ms Testing a5 latency average = 998.176 ms Testing a6 latency average = 979.954 ms Testing a7 latency average = 1066.523 ms Testing a8 latency average = 1030.235 ms I then tested a Power8 machine (also kernel 3.10 gcc 4.8). Configure reports "checking for __builtin_prefetch... yes", but I don't think it does anything here, as the results are within noise level. A quick search didn't turn up anything informative on this platform, and I'm not motivated to dig deeper. In any case, it doesn't make things worse. HEAD: Testing a1 latency average = 1402.163 ms Testing a2 latency average = 1442.971 ms Testing a3 latency average = 1599.188 ms Testing a4 latency average = 1664.397 ms Testing a5 latency average = 1782.091 ms Testing a6 latency average = 1860.655 ms Testing a7 latency average = 1929.120 ms Testing a8 latency average = 2021.100 ms 0001+0005: Testing a1 latency average = 1433.080 ms Testing a2 latency average = 1428.369 ms Testing a3 latency average = 1542.406 ms Testing a4 latency average = 1642.452 ms Testing a5 latency average = 1737.173 ms Testing a6 latency average = 1828.239 ms Testing a7 latency average = 1920.909 ms Testing a8 latency average = 2036.922 ms [1] https://www.postgresql.org/message-id/CAFBsxsHqmH_S%3D4apc5agKsJsF6xZ9f6NaH0Z83jUYv3EgySHfw%40mail.gmail.com -- John Naylor EDB: http://www.enterprisedb.com
