On Thu, Apr 22, 2021 at 03:52:32PM -0400, Bruce Momjian wrote: > On Thu, Apr 22, 2021 at 09:45:15PM +0200, Luca Ferrari wrote: > > Hi all, > > I'm unable to find (apparently) a way to find out a possible value to > > start with for effective_io_concurrency. > > I suspect that benchmarking, e.g., using bonnie++ or sysbench and > > testing with different values of concurrency could help to determine > > the max number of concurrent request, (tps, lower latency, ecc.). > > Is thjs correct or is there another suggested way? > > I recommend 256 for SSDs or other RAM-like fsync systems, and maybe > maybe 16 for magnetic. Note that the interpretation of this GUC changed in v13. https://www.postgresql.org/docs/13/release-13.html |Change the way non-default effective_io_concurrency values affect concurrency (Thomas Munro) |Previously, this value was adjusted before setting the number of concurrent requests. The value is now used directly. Conversion of old values to new ones can be done using: |SELECT round(sum(OLDVALUE / n::float)) AS newvalue FROM generate_series(1, OLDVALUE) s(n); -- Justin
