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Re: avoid Computing Guix derivation when not necessary
From: |
zimoun |
Subject: |
Re: avoid Computing Guix derivation when not necessary |
Date: |
Mon, 13 Feb 2023 11:37:18 +0100 |
Hi,
On Sun, 12 Feb 2023 at 01:10, Ludovic Courtès <ludo@gnu.org> wrote:
>> The principle is simple: get commit and directory info from the profile
>> manifest, compare commits, if commits for all channels are the same, do
>> not try to update the profile.
Indeed, some improvements could be done in that direction. For
instance,
--8<---------------cut here---------------start------------->8---
$ guix describe
Generation 89 Jan 17 2023 15:20:08 (current)
guix 29efa27
repository URL: https://git.savannah.gnu.org/git/guix.git
branch: master
commit: 29efa2791dafb042ca8ace77bcf8538fb404d492
$ guix pull --commit=29efa27
Updating channel 'guix' from Git repository at
'https://git.savannah.gnu.org/git/guix.git'...
Building from this channel:
guix https://git.savannah.gnu.org/git/guix.git 29efa27
Computing Guix derivation for 'x86_64-linux'... |
[...]
--8<---------------cut here---------------end--------------->8---
Going from one commit to the exact same commit should not trigger some
intensive «Computing Guix derivation».
Note that if I run “guix pull --commit=29efa27” two times in row, the
second one it displays: «nothing to be done» after «Computing Guix
derivation».
Last, note that:
/var/guix/profiles/per-user/simon/current-guix -> current-guix-90-link
and
--8<---------------cut here---------------start------------->8---
$ /var/guix/profiles/per-user/simon/current-guix-90-link/bin/guix describe
guix 29efa27
repository URL: https://git.savannah.gnu.org/git/guix.git
commit: 29efa2791dafb042ca8ace77bcf8538fb404d492
$ /var/guix/profiles/per-user/simon/current-guix-89-link/bin/guix describe
guix 29efa27
repository URL: https://git.savannah.gnu.org/git/guix.git
branch: master
commit: 29efa2791dafb042ca8ace77bcf8538fb404d492
$ readlink -f /var/guix/profiles/per-user/simon/current-guix-90-link
/gnu/store/g32zjrbr40fzp1rj5i6gx7hal20myfyv-profile
$ readlink -f /var/guix/profiles/per-user/simon/current-guix-89-link
/gnu/store/pk1i1dsagdby5pqydmvfbffg0i80wwvy-profile
$ diff -r --no-dereference \
/gnu/store/g32zjrbr40fzp1rj5i6gx7hal20myfyv-profile/manifest \
/gnu/store/pk1i1dsagdby5pqydmvfbffg0i80wwvy-profile/manifest
12c12
< "/gnu/store/96bibk75vy5yvmilnycd8pl0l2bydcww-guix-29efa2791"
---
> "/gnu/store/ldp0snjsac6hp1fikk5b8413pihm77di-guix-29efa2791"
20c20
< (branch #f)
---
> (branch "master")
--8<---------------cut here---------------end--------------->8---
Hum, maybe I have something twisted somewhere in my configuration. From
my understanding, it comes from (guix scripts pull):
--8<---------------cut here---------------start------------->8---
(match (find guix-channel? channels)
((? channel? guix)
;; Apply '--url', '--commit', and '--branch' to the 'guix' channel.
(let ((url (or url (channel-url guix))))
(cons (match ref
(('commit . commit)
(channel (inherit guix)
(url url) (commit commit) (branch #f)))
--8<---------------cut here---------------end--------------->8---
where ’branch’ should not be #f but instead inherit from ’guix’. I
remember discussing this but I do not find where. :-)
> One marginal improvement would be sharing the cache that ‘time-machine’
> uses with ‘guix pull’. Last I looked it wasn’t as easy as one might
> hope, but I forgot the details.
It could be nice! :-) Last time I gave a look, I had an headache. ;-)
Cheers,
simon