Re: Faster!

[Ludovic Courtès]

The saga continues!

With today’s commit, the execution time of

  guix build -e '(@ (gnu packages emacs) emacs)' -d

is down from 1.54s to 1.08s on my 2.6 GHz laptop.  That’s 30%.  :-)

The head of the profile is now like this:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,pr (package-derivation s emacs)
%     cumulative   self
time   seconds     seconds      name
 29.07      0.35      0.33  write
  8.14      0.09      0.09  search-path
  6.98      0.09      0.08  open-file
  5.81      0.07      0.07  read
  4.65      0.51      0.05  call-with-output-string
  4.65      0.05      0.05  %after-gc-thunk
  3.49      0.04      0.04  hash-ref
  2.33      0.24      0.03  write-derivation
  2.33      0.07      0.03  bytevector-quintet-fold-right
  2.33      0.03      0.03  #<procedure 23dc1c0 (_ _ _ _)>
  2.33      0.03      0.03  hash-set!
  2.33      0.03      0.03  display
[...]
  0.00      0.79      0.00  build-expression->derivation
[...]
---
Sample count: 86
Total time: 1.125903012 seconds (0.152722833 seconds in GC)
--8<---------------cut here---------------end--------------->8---

IOW, the main bottleneck is in Guile’s ‘write’ and port output (as
called from ‘build-expression->derivation’).

We also do a lot of GC.  This could be improved by optimizing the RPCs
in store.scm to allocate less.

Ludo’.