Horton

Re: JIT compiling with LLVM v11

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-03-09T20:42:24Z
Lists: pgsql-hackers 
On 3/6/18 10:29, Peter Eisentraut wrote:
> I think taking the total cost as the triggering threshold is probably
> good enough for a start.  The cost modeling can be refined over time.

I looked into this a bit more.

The default of jit_above_cost = 500000 seems pretty good.  I constructed
a query that cost about 450000 where the run time with and without JIT
were about even.  This is obviously very limited testing, but it's a
good start.

For jit_optimize_above_cost, in my testing, any query where JIT payed
off was even faster with optimizing.  So right now I don't see a need to
make this a separate setting.  Maybe just make it an on/off setting for
experimenting.

For inlining, I haven't been able to get a clear picture.  It's a bit
faster perhaps, but the optimizing dominates it.  I don't have a clear
mental model for what kind of returns to expect from this.

What I'd quite like is if EXPLAIN or EXPLAIN ANALYZE showed something
about what kind of JIT processing was done, if any, to help with this
kind of testing.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Improve JIT docs.

  2. Add documentation for the JIT feature.

  3. Add EXPLAIN support for JIT.

  4. Add inlining support to LLVM JIT provider.

  5. JIT tuple deforming in LLVM JIT provider.

  6. Add FIELDNO_* macro designating offset into structs required for JIT.

  7. Add expression compilation support to LLVM JIT provider.

  8. Expand list of synchronized types and functions in LLVM JIT provider.

  9. Add helpers for emitting LLVM IR.

  10. Basic planner and executor integration for JIT.

  11. Debugging and profiling support for LLVM JIT provider.

  12. Support for optimizing and emitting code in LLVM JIT provider.

  13. Add file containing extensions of the LLVM C API.

  14. Basic JIT provider and error handling infrastructure.

  15. Add configure infrastructure (--with-llvm) to enable LLVM support.

  16. Add C++ support to configure.

  17. Add PGAC_PROG_VARCC_VARFLAGS_OPT autoconf macro.

  18. Fix VM buffer pin management in heap_lock_updated_tuple_rec().

  19. Allow tupleslots to have a fixed tupledesc, use in executor nodes.

  20. Expression evaluation based aggregate transition invocation.

  21. Perform slot validity checks in a separate pass over expression.

  22. Rely on executor utils to build targetlist for DML RETURNING.

  23. Refer to OS X as "macOS", except for the port name which is still "darwin".