Re: JIT compiling with LLVM v9.0

Tomas Vondra <tomas.vondra@2ndquadrant.com>

From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
Date: 2018-02-05T22:27:01Z
Lists: pgsql-hackers

Attachments

Hi,

On 02/03/2018 01:05 PM, Tomas Vondra wrote:
> Hi,
> 
> ...
> 
> In this round of tests I've disabled parallelism. Based on
> discussion with Andres I've decided to repeat the tests with parallel
> queries enabled - that's running now, and will take some time to
> complete.
> 

And here are the results with parallelism enabled - same machines, but
with max_parallel_workers_per_gather > 0. Based on discussions and
Andres' FOSDEM talk I somehow expected more significant JIT benefits in
the parallel case, but the results are pretty much exactly the same
(modulo speedup thanks to parallelism, of course).

In fact, the JIT impact is much noisier with parallelism enabled, for
some reason, with regressions where there were no measurable regressions
before (particularly for the 10GB case).

That is not to say we shouldn't be doing JIT, or that Andres did not
observe the speedups/benefits he mentioned during the talk - I have no
trouble believing it depends on queries, and DBT-3 may not match that.


I don't plan doing any further benchmarks on this patch series unless
someone requests that (possibly with ideas what to focus on). I'll keep
looking at the patch, of course. I've seen some build issues, so I'll
try finding more details.


regards

-- 
Tomas Vondra                  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".