> .. optimisation flags like O3
> And please suggest ... to check on the performance difference
The Phoronix has been tested the PostgreSQL 13 with Clang 12 + GCC 11.1 On Xeon Ice Lake
"The CFLAGS/CXXFLAGS set throughout testing were "-O3 -march=native -flto"
as would be common for HPC systems when building performance sensitive code."
and the results:
only the Postgres ( GCC 11 vs. LLVM Clang 12 Benchmarks On Xeon Ice Lake )
maybe you can replicate the Phoronix results ( but this is only gcc11.1 ! )
"Compare your own system(s) to this result file with the Phoronix Test Suite
by running the command: phoronix-test-suite benchmark 2105299-IB-COMPILERT91"
Regards.
Imre
Hi PostgreSQLv14 source code build with GCCv11.2 and Clangv12(without JIT) with optimisation flags like O3 and tested with HammerDB
Observed TPC-H , GCC performance better than Clang(without JIT). The performance difference ~22% and also noticed the assembly code difference GCC vs Clang( e.g. GCC inlined functionality compared to Clang).
Environment details:
————————-
OS :RHEL8.4
Bare metal : Apple/AMD EPYC/IBM
Test(TPC-H) Benchmark Environment:HammerDB
Is the performance difference mainly because of below points ?
1 data over flow and calculations like int128(int128.c) and C arithmetic operations(functions include in float.h e.g float4_mul)
And please suggest is any another functionality or code points need to check on the performance difference
