Yes, currently focusing affects queries as well. In meanwhile on analysis(hardware level) and sample examples noticed 1. GCC performance better than Clang on int128 . 2. Clang performance better than GCC on long long the reference example https://stackoverflow.com/questions/63029428/why-is-int128-t-faster-than-long-long-on-x86-64-gcc
3.GCC enabled with “ fexcess-precision=standard” (precision cast for floating point ). Is these 3 points can make performance difference GCC vs Clang in PostgreSQLv14 in Apple/AMD/()environment(intel environment need to check). In these environment int128 enabled wrt PostgreSQLv14. On Friday, November 5, 2021, Tomas Vondra <tomas.von...@enterprisedb.com> wrote: > Hi, > > IMO this thread provides so little information it's almost impossible to > answer the question. There's almost no information about the hardware, > scale of the test, configuration of the Postgres instance, the exact build > flags, differences in generated asm code, etc. > > I find it hard to believe merely switching from clang to gcc yields 22% > speedup - that's way higher than any differences we've seen in the past. > > In my experience, the speedup is unlikely to be "across the board". There > will be a handful of affected queries, while most remaining queries will be > about the same. In that case you need to focus on those queries, see if the > plans are the same, do some profiling, etc. > > > regards > > -- > Tomas Vondra > EnterpriseDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company >
