Re: MPS: profiler

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: Ihor Radchenko <yantar92@posteo.net>,  Eli Zaretskii <eliz@gnu.org>,
>   emacs-devel@gnu.org
> Date: Fri, 21 Jun 2024 10:31:55 +0200
> 
> Helmut Eller <eller.helmut@gmail.com> writes:
> 
> > On Fri, Jun 21 2024, Gerd Möllmann wrote:
> >
> >>> There is a function mps_arena_busy, that might be useful.  The doc says
> >>> that it should only be used for debugging.  But the implementation
> >>> actually checks if the arena holds a lock.
> >>
> >> Yes, the SIBPROF handler could at least return early then.
> >
> > Perhaps something like this?
> 
> Not sure. The result of is_busy is only valid at the point in time when
> it is called.

Are you thinking about what happens when GC is run concurrently?
Because this is not what happens here, AFAIU.  Let's focus on fixing
the actual issue we see in the backtrace, and consider its possible
generalizations later.

Are you saying that is_busy could return false in the situation we see
in the backtrace, i.e. during the entire time MPS processes its
protection-induced SIGSEGV?