Ants Aasma <ants.aa...@eesti.ee> wrote: > Concurrency 8 results should probably be ignored - variance was > huge, definitely more than the differences. I'm not so sure it should be ignored -- one thing I noticed in looking at the raw numbers from my benchmarks was that the -O2 code was much more consistent from run to run than the -O3 code. I doubt that the more aggressive optimizations were developed under NUMA architecture, and I suspect that the aggressively optimized code may be more sensitive to whether memory is directly accessed by the core running the process or routed though the memory controller on another core. (I hit on this idea this morning when I remembered seeing similar variations in run times of STREAM against our new servers with NUMA.) This suggests that in the long term, it might be worth investigating whether we can arrange for a connection's process to have some degree of core affinity and encourage each process to allocate local memory from RAM controlled by that core. To some extent I would expect the process-based architecture of PostgreSQL to help with that, as you would expect a NUMA-aware OS to try to arrange that to some degree. -Kevin
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