Re: igc statistics display

[Eli Zaretskii <eliz@gnu.org>]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: Emacs Devel <emacs-devel@gnu.org>
> Date: Fri, 10 Jan 2025 08:31:29 +0100
> 
> On Fri, Jan 10 2025, Gerd Möllmann wrote:
> 
> > I wonder if something like that wouldn't be interesting for Emacs also
> > beyond monitoring GC activity.
> 
> There are many potentially interesting events
>   - begin/end of a command
>   - begin/end of a redisplay
>   - cache misses (regexp cache, charpos cache ..)
>   - begin/end of interval rebalancing?
>   - call/return of Lisp functions
> 
> It's a bit annyoing that drace/systemtap needs special permissions.  In
> theory, systemtap has a "dyninst runtime" that uses ptrace instead of
> uprobes and hence would not need special permissions (at least not more
> than gdb).  In practice, the dyninst runtime doesn't seem to work yet:
> it exist with a segfault.
> 
> It would also be useful to have some helper functions (called tapsets in
> systemtap) to write dtrace/systemtap scripts, e.g. accessing symbol-name
> etc.

SystemTap is not the ideal means for such a facility.  Its only
significant advantage is that it's supported by GDB.  But its huge
disadvantage is that it's a Linux-only facility.

In addition, I feel that this is too low-level for our purposes.  We
need something more akin to trace-redisplay.