Subject: Re: bug#44175: [optimization] Grafting is too slow

From: Ludovic Courtès <[email-masked]>
Date: Fri, 23 Oct 2020 23:17:49 +0200

Maxim Cournoyer <[email-masked]> skribis:

> Lars-Dominik Braun <[email-masked]> writes:
>
>> Hi Maxim,
>>
>>> Judging from the above, it seems this issue has been resolved.
>> grafting is still a performance issue imo. Compare for example:
>>
>> $ time guix environment --ad-hoc  --search-paths r-learnr
>> guix environment --ad-hoc --search-paths r-learnr  5,90s user 0,09s system 210% cpu 2,844 total
>> $ time guix environment --ad-hoc  --search-paths r-learnr --no-grafts
>> guix environment --ad-hoc --search-paths r-learnr --no-grafts  2,03s user 0,08s system 164% cpu 1,277 total
>
> I'm opening a new issue to track optimizing the grafting code, since
> it's independent of environments (grafts are applied anytime a
> derivation is built, AFAICT).  Grafting is inherently IO-bound,

What is slow above is not grafting itself: it’s determining what to
graft that takes CPU time.

I had reopened the initial bug at <https://issues.guix.gnu.org/41702>;
should we close this one?

Thanks,
Ludo’.