Horton

Re: JIT compiling with LLVM v12

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Noah Misch <noah@leadboat.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, pgsql-hackers@postgresql.org
Date: 2018-09-05T18:55:39Z
Lists: pgsql-hackers 
Hi,

On 2018-08-22 06:20:21 +0000, Noah Misch wrote:
> I see jit slows the regression tests considerably:

Is this with LLVM assertions enabled or not?  The differences seem
bigger than what I'm observing, especially on the mips animal - which I
observe uses a separately installed LLVM build.

On my machine, with master, on a postgres assert build w/ non-debug llvm build:
PGOPTIONS='-c jit=0' time make -Otarget -j10 -s check-world  && echo success || echo f
240.37user 55.55system 2:08.17elapsed 230%CPU (0avgtext+0avgdata 66264maxresident)k

PGOPTIONS='-c jit=1' time make -Otarget -j10 -s check-world  && echo success || echo f
253.02user 55.77system 2:16.22elapsed 226%CPU (0avgtext+0avgdata 54756maxresident)k


Using your command, on a postgres optimized build w/ non-debug llvm build:

> # x86_64, non-assert, w/o llvm
> $ for n in 1 2 3; do env time make -C src/bin/pg_upgrade check; done 2>&1 | grep elapsed
> 7.64user 4.24system 0:36.40elapsed 32%CPU (0avgtext+0avgdata 36712maxresident)k
> 8.09user 4.50system 0:37.71elapsed 33%CPU (0avgtext+0avgdata 36712maxresident)k
> 7.53user 4.18system 0:36.54elapsed 32%CPU (0avgtext+0avgdata 36712maxresident)k
>
> # x86_64, non-assert, w/  llvm trunk
> $ for n in 1 2 3; do env time make -C src/bin/pg_upgrade check; done 2>&1 | grep elapsed
> 9.58user 5.79system 0:49.61elapsed 30%CPU (0avgtext+0avgdata 36712maxresident)k
> 9.47user 5.92system 0:47.84elapsed 32%CPU (0avgtext+0avgdata 36712maxresident)k
> 9.09user 5.51system 0:47.94elapsed 30%CPU (0avgtext+0avgdata 36712maxresident)k
>

andres@alap4:~/build/postgres/master-optimize/vpath$ for n in 1 2 3; do PGOPTIONS='-cjit=0' env time make -C src/bin/pg_upgrade check; done 2>&1 | grep elapsed
8.01user 3.63system 0:39.88elapsed 29%CPU (0avgtext+0avgdata 50196maxresident)k
7.96user 3.86system 0:39.70elapsed 29%CPU (0avgtext+0avgdata 50064maxresident)k
7.96user 3.80system 0:37.17elapsed 31%CPU (0avgtext+0avgdata 50148maxresident)k
andres@alap4:~/build/postgres/master-optimize/vpath$ for n in 1 2 3; do PGOPTIONS='-cjit=1' env time make -C src/bin/pg_upgrade check; done 2>&1 | grep elapsed
7.88user 3.76system 0:44.98elapsed 25%CPU (0avgtext+0avgdata 50092maxresident)k
7.99user 3.72system 0:46.53elapsed 25%CPU (0avgtext+0avgdata 50036maxresident)k
7.88user 3.87system 0:45.26elapsed 25%CPU (0avgtext+0avgdata 50132maxresident)k

So here the difference is smaller, but not hugely so.


> # mips32el, assert, w/o llvm (buildfarm member topminnow) [1]
> 28min install-check-*
> 35min check-pg_upgrade
>
> # mips32el, assert, w/  llvm 6.0.1 [1]
>  63min install-check-*
> 166min check-pg_upgrade

But this seems so absurdly large of a difference that I kinda think LLVM
assertions (wich are really expensive and add O(N) operations in a bunch
of places) might be to blame.

Greetings,

Andres Freund

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".