On Thu, Apr 22, 2021 at 09:54:56PM +0200, Luca Ferrari wrote: > On Thu, Apr 22, 2021 at 9:52 PM Bruce Momjian <bruce@xxxxxxxxxx> 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. > > > Thanks Bruce, this is a very good starting point. > But is there a rationale about those numbers? I mean, if I change the > storage system, how should I set a correct number? Uh, you need to study the queue length of the device to see how many concurrent requests it can process. -- Bruce Momjian <bruce@xxxxxxxxxx> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
