Subject: Re: bug#39341: Installer using 100% of a CPU core
From: Ludovic Courtès <[email-masked]>
To: Maxim Cournoyer <[email-masked]>
Cc: Mathieu Othacehe <[email-masked]>, [email-masked], "pelzflorian \(Florian Pelz\)" <[email-masked]>
Date: Sun, 25 Apr 2021 23:41:59 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi!

(Cc: Florian + Mathieu)

Maxim Cournoyer <[email-masked]> skribis:

> While using the Guix 1.0.1 installer, I noticed that it was constantly
> maxing one of the cores on the machine.
>
> The guilty process is:
>
> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> root       377 99.8  0.3  37268 10328 ?        Rs   08:20 377:09 /gnu/store/8asv37pjsq3n4b4hgz9ys840f9j531hk-kmscon-0.0.0-1.01dd0a2/libexec/kmscon/kmscon --login --vt tty1 --no-switchvt --login -- /gnu/store/cb92798ps1xpla3ai14ik81vkl7jbw97-installer -p

Good news!  This is finally fixed:

  https://git.savannah.gnu.org/cgit/guix.git/commit/?id=d904abe0768293b2322dbf355b6e41d94e769d78

(Mathieu, Florian: let me know if anything looks fishy.)

The commit log says it all.  With this patch, a new FIFO is opened after
each keymap-change request so kmscon no longer polls on a stale file
descriptor.

I’ve verified that keymap choices in the installer are honored, that you
can change anytime via the F1 menu, and that there’s no file descriptor
leak in the kmscon process.

Now people will be less likely to hear the fan of their laptop right
from the start of the installation process.  :-)

Ludo’.