JIT: So you want to be faster than an interpreter on modern CPUs
a day ago
- #JIT Compiler
- #Performance Optimization
- #PostgreSQL
- The blog discusses the challenges of optimizing a JIT compiler for PostgreSQL, focusing on performance improvements over the interpreter.
- Modern CPUs with out-of-order execution and branch prediction complicate performance optimization efforts.
- The interpreter's main loop with opcode dispatch can be inefficient due to unpredictable branching, leading to performance losses.
- Using 'computed gotos' instead of a switch statement can improve interpreter performance by making jumps more predictable.
- Optimizing a simple query like 'SELECT a FROM table WHERE a = 42' involves reducing unnecessary null checks and inlining common operations.
- Inlining the int4eq function call significantly reduces instruction count and improves performance.
- The author explores various optimizations, including removing null checks and inlining, showing measurable performance gains.
- Despite CPU optimizations, the interpreter remains a tough competitor, but the JIT compiler shows promise with further improvements.
- The author seeks collaboration and support for the project, including code contributions, sponsoring, or job offers.