Re: Shrinking the C core

[Immanuel Litzroth]

On Fri, Aug 11, 2023 at 2:04 AM Christopher Dimech <dimech@gmx.com> wrote:
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>
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> > Sent: Friday, August 11, 2023 at 11:49 AM
> > From: "Eric S. Raymond" <esr@thyrsus.com>
> > To: "Eli Zaretskii" <eliz@gnu.org>
> > Cc: luangruo@yahoo.com, emacs-devel@gnu.org
> > Subject: Re: Shrinking the C core
> >
> > Eli Zaretskii <eliz@gnu.org>:
> > > What's more, Emacs is still a single-threaded Lisp machine, although
> > > in the last 10 years CPU power develops more and more in the direction
> > > of multiple cores and execution units, with single execution units
> > > being basically as fast (or as slow) today as they were a decade ago.
> >
> > Yeah, I've been thinking hard about that single-threadedness in the
> > last couple of weeks.  I have a design sketch in my head for a
> > re-partitioning of Emacs into a front-end/back-end pair communicating
> > via sockets, with the back end designed to handle multiple socket
> > sessions for collaborative editing. (No, this isn't my big secret idea,
> > it's something I think should be done *along with* my big secret idea.)
> >
> > For this to work, a lot of what is now global state would need to be
> > captured into a structure associated with each socket session.  I notice
> > that it's difficult to find an obviously correct cut line between what
> > the session structure should own and what still needs to be shared state;
> > like, *some* keymaps definitely need to be session and buffers still need
> > to be shared, but what about the buffer's mode set and mode-specific kemaps?
> > Or marks?  Or overlays?
> >
> > This is a difficult design problem because of some inherent features
> > of the Emacs Lisp language model.  I did not fail to notice that those
> > same features would make exploiting concurrency difficult even in the
> > present single-user-only implementation.  It is unclear what
> > could be done to fix this without significant language changes.
> >
> > > And if these theoretical arguments don't convince you, then there are
> > > facts: the Emacs display engine, for example, was completely rewritten
> > > since the 1990s, and is significantly more expensive than the old one
> > > (because it lifts several of the gravest limitations of the old
> > > redisplay).  Similarly with some other core parts and internals.
> >
> > Are you seriously to trying to tell me that the display engine rewrite ate
> > *three orders of magnitude* in machine-speed gains?  No sale.  I have
> > some idea of the amount of talent on the devteam and I plain do not
> > believe y'all are that incompetent.
> >
> > > We found this conclusion to be false in practice, at least in Emacs
> > > practice.
> >
> > I'm not persuaded, because your causal account doesn't pass my smell
> > test. I think you're misdiagnosing the performance problems through
> > being too close to them. It would take actual benchmark figures to
> > persuade me that Lisp interpretive overhead is the actual culprit.
> >
> > Your project, your choices. But I have a combination of experience
> > with the code going back nearly to its origins with an outside view of
> > its present strate, and I think you're seeing your own assumptions
> > about performance lag reflected back at you more than the reality.
> >
> > > Please be more patient,
> >
> > That *was* patient.
>
> > I didn't aim for his head until the *second* time he poked me. :-)
>
> Good you're not a general in a battlefield !  I don't have such rules of 
> conduct.
> Did you know that there are tribes in the Amazon River Basin who simply kill
> you if they see you ?
How did those tribes get to know about Eric?
i
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