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Re: Compilation time with Guile 3.0.3-to-be
From: |
Andy Wingo |
Subject: |
Re: Compilation time with Guile 3.0.3-to-be |
Date: |
Thu, 04 Jun 2020 11:50:29 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Hi :)
On Thu 04 Jun 2020 09:50, Ludovic Courtès <ludo@gnu.org> writes:
> With the attached patch I’ve run ‘make as-derivation’ (equivalent to
> ‘guix pull’) and timed the builds of guix-packages-base.drv (279 files)
> and guix-packages.drv (217 files) on my 4-core i7 laptop:
>
> • guix-packages-base.drv: 1m30s (was 4m)
>
> • guix-packages.drv: 30s (was 1m8s)
Nice!! Thanks for testing :-)
> For the record, the optimizations currently used in (guix build compile)
> are between the new -O0 and -O1:
>
> (cond ((or (string-contains file "gnu/packages/")
> (string-contains file "gnu/tests/"))
> ;; Level 0 is good enough but partial evaluation helps preserve the
> ;; "macro writer's bill of rights".
> (override-option #:partial-eval? #t
> (optimizations-for-level 0)))
Here fwiw I would use -O1. It is basically the same as -O0 except that
it adds partial evaluation and it inlines primcalls. If you are willing
to do partial evaluation, you are probably willing to inline primcalls
too; I think it typically leads to less code and the compilation time is
similar to -O0.
> ((string-contains file "gnu/services/")
> ;; '-O2 -Ono-letrectify' compiles about ~20% faster than '-O2' for
> ;; large files like gnu/services/mail.scm.
> (override-option #:letrectify? #f
> (optimizations-for-level 2)))
Interesting. I think this is probably a bug of some sort that we'll
have to keep working on.
> With the new -O1, the scheme->tree-il conversion (mostly macro
> expansion) accounts for half of the build time on large files:
>
> scheme@(guile-user)> ,use(system base optimize)
> scheme@(guile-user)> ,time (compile-file "gnu/packages/python-xyz.scm" #:opts
> (optimizations-for-level 1))
> $1 =
> "/data/src/guile-3.0/cache/guile/ccache/3.0-LE-8-4.3/home/ludo/src/guix/gnu/packages/python-xyz.scm.go"
> ;; 4.154311s real time, 5.604945s run time. 2.538106s spent in GC.
Interesting data :)
Note that in 3.0.3 there is also a new phase called "lowering". Before
a compiler from Tree-IL to language X is called, the tree-IL program is
"lowered" -- meaning canonicalized and optionally optimized.
(define (lower-exp exp env optimization-level opts)
(let ((make-lowerer (language-lowerer (lookup-language 'tree-il))))
((make-lowerer optimization-level opts) exp env)))
Similarly there is an analysis pass for warnings, which runs before
lowering:
(define (analyze-exp exp env warning-level warnings)
(let ((make-analyzer (language-analyzer (lookup-language 'tree-il))))
((make-analyzer warning-level warnings) exp env)))
These can be interesting to test different phases of the tree-il ->
bytecode path.
> The profile looks like this:
>
> scheme@(guile-user)> ,pr (define t (call-with-input-file
> "gnu/packages/python-xyz.scm" (lambda (port) (read-and-compile port #:to
> 'tree-il))))
> % cumulative self
> time seconds seconds procedure
> 13.16 0.45 0.40 anon #x1136458
> 10.53 0.35 0.32 ice-9/popen.scm:168:0:reap-pipes
> 7.89 0.24 0.24 anon #x1132af8
> 6.14 0.35 0.19 ice-9/boot-9.scm:3128:0:module-gensym
> 5.26 0.21 0.16 ice-9/boot-9.scm:2201:0:%load-announce
> 4.39 0.19 0.13 ice-9/psyntax.scm:749:8:search
> 3.51 0.69 0.11 ice-9/psyntax.scm:2964:6:match*
> 3.51 0.11 0.11 anon #x11334e8
> 3.51 0.11 0.11 anon #x1136428
> 2.63 0.08 0.08 anon #x113a258
> 1.75 0.05 0.05 ice-9/psyntax.scm:3017:12:$sc-dispatch
> 1.75 0.05 0.05 anon #x1139e68
> 0.88 277.30 0.03 ice-9/boot-9.scm:220:5:map1
>
> It’d be great to waive the anonymity of that first lambda. :-)
I think I just fixed it :)
> I was wondering what fraction of that time was spent running Guix macros
> (‘package’, ‘base32’, and so on), but it’s difficult to answer that
> question here. Probably something to investigate so we can make further
> progress!
I think the reap-pipes call is a pretty bad sign, incidentally!
Cheers,
Andy