Re: igc, macOS avoiding signals

[Eli Zaretskii]

> Date: Sat, 28 Dec 2024 18:40:30 +0000
> From: Pip Cet <pipcet@protonmail.com>
> Cc: spd@toadstyle.org, gerd.moellmann@gmail.com, emacs-devel@gnu.org
> 
> "Eli Zaretskii" <eliz@gnu.org> writes:
> 
> >> Date: Sat, 28 Dec 2024 15:12:23 +0000
> >> Cc: gerd.moellmann@gmail.com, emacs-devel@gnu.org
> >> From:  Pip Cet via "Emacs development discussions." <emacs-devel@gnu.org>
> >>
> >> I think we probably need to put instrumentation in the source code, so
> >> we gain some idea of how long signals are delayed for when we mark them
> >> pending.
> >
> > What do we expect to learn from this,
> 
> It tests the current code, which does this:
> 
> When a signal arrives, and we can't handle it because we might have
> interrupted MPS, we mark the signal as pending in the igc structure.  At
> some point later, we check the igc structure for pending signals,
> reraise them, and unmask them.
> 
> Gerd's experience suggests that the "some point later" happens too late.
> This patch gives us measurements.
> 
> It's unrelated to the OS scheduler, AFAICS.

Ah, okay.  I note that if we'd block signals when calling MPS and
unblock on exit, then these delays couldn't have happened, AFAIU.