bug#67502: closed ([Cuirass] ‘cuirass remote-worker’ gets the CPU count wrong on the OverDrive)

[GNU bug Tracking System]

Your message dated Tue, 28 Nov 2023 16:28:50 +0100
with message-id <87cyvtsxql.fsf@gnu.org>
and subject line Re: bug#67502: [Cuirass] ‘cuirass remote-worker’ gets the CPU 
count wrong on the OverDrive
has caused the debbugs.gnu.org bug report #67502,
regarding [Cuirass] ‘cuirass remote-worker’ gets the CPU count wrong on the 
OverDrive
to be marked as done.

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67502: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67502
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> --- Begin Message ---
>
>
>
> Subject: 
>
> [Cuirass] ‘cuirass remote-worker’ gets the CPU count wrong on the OverDrive
>
>
>
>
> Date: 
>
> Tue, 28 Nov 2023 10:09:42 +0100
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13)
>
>
>
>
> On the OverDrive (AArch64), ‘cuirass remote-worker’ (1.2.0-1.bdc1f9f) says:
>
>   starting 2 workers (parallelism: 1 cores) for server at 10.0.0.1
>
> Instead it should use two cores for each worker:
>
> --8<---------------cut here---------------start------------->8---
> ludo@dover ~$ guile -c '(use-modules (ice-9 threads)) (pk 
> (current-processor-count))'
>
> ;;; (4)
> ludo@dover ~$ guile -c '(use-modules (ice-9 threads)) (pk (ceiling-quotient 
> (current-processor-count) 2))'
>
> ;;; (2)
> ludo@dover ~$ nproc
> 4
> --8<---------------cut here---------------end--------------->8---
>
> Since ‘current-processor-count’ is implemented indirectly in terms of
> ‘sched_getaffinity’, this suggests that the process starts with a bogus
> affinity mask.  (Time passes…)  That’s indeed the case:
>
> --8<---------------cut here---------------start------------->8---
> ludo@dover ~$ sudo herd status cuirass-remote-worker
> Status of cuirass-remote-worker:
>   It is started.
>   Running value is 21279.
>   It is enabled.
>   Provides (cuirass-remote-worker).
>   Requires (avahi-daemon guix-daemon networking).
>   Will be respawned.
> ludo@dover ~$ guile -c '(pk (getaffinity 21279))'
>
> ;;; 
> (#*1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000)
> --8<---------------cut here---------------end--------------->8---
>
> Compare to the affinity mask on x86_64-linux-gnu:
>
> --8<---------------cut here---------------start------------->8---
> ludo@guix-hpc3 ~$ sudo guile -c '(pk (getaffinity 1817))'
>
> ;;; 
> (#*1111111111111111111111111111111100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000)
> --8<---------------cut here---------------end--------------->8---
>
> Interesting that the initial affinity mask differs on aarch64-linux-gnu
> compared to x86_64-linux-gnu.
>
> Ludo’.
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#67502: [Cuirass] ‘cuirass remote-worker’ gets the CPU count wrong on the OverDrive
>
>
>
>
> Date: 
>
> Tue, 28 Nov 2023 16:28:50 +0100
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13)
>
>
>
>
> Ludovic Courtès <ludovic.courtes@inria.fr> skribis:
>
> > ludo@dover ~$ sudo herd status cuirass-remote-worker
> > Status of cuirass-remote-worker:
> >   It is started.
> >   Running value is 21279.
> >   It is enabled.
> >   Provides (cuirass-remote-worker).
> >   Requires (avahi-daemon guix-daemon networking).
> >   Will be respawned.
> > ludo@dover ~$ guile -c '(pk (getaffinity 21279))'
> >
> > ;;; 
> > (#*1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000)
>
> This was due to ‘run-fibers’ binding one thread per CPU core.  Thus,
> calling ‘getaffinity’ from within ‘run-fibers’ shows only one CPU and
> likewise ‘current-processor-count’ returns 1.
>
> Fixed in Cuirass commit 87a6d6ea7ae79fdf487bbcfd44bb3dce2d7c6e82.
>
> Ludo’.
>
>
> --- End Message ---