bug#74357: c-mode: Some syntactic constructs cause unreasonable typing lag

["Björn Lindqvist" <bjourne@gmail.com>]

Hello Alan,

Now I rebuilt emacs from scratch with patches. Though there is still
some lag, on my degenerate test case there is a substantial
improvement! I can't try the patches on my slow computer since
building emacs on it takes too long. But I'll try it on the next emacs
release.

Den lör 30 nov. 2024 kl 19:33 skrev Alan Mackenzie <acm@muc.de>:
>
> Hello, Björn.
>
> Thanks for such a prompt reply.
>
> On Sat, Nov 30, 2024 at 19:04:31 +0100, Björn Lindqvist wrote:
> > Hello Alan,
>
> > I applied your patch (patch < patch.diff), then I byte-compiled the
> > changed elisp files (emacs -batch -f batch-byte-compile cc-engine.el,
> > emacs -batch -f batch-byte-compile cc-mode.el), and then I installed
> > them over the existing .elc files. Maybe I applied the patch wrong
> > because it didn't improve performance. You can find a new profiler
> > report here:
>
> > https://gist.github.com/bjourne/c715e15729c841d1f68e00499c622d77
>
> Sorry it hasn't worked, yet.
>
> I've had a look at that profiler report, and it seems clear that it's
> profiling something without the patch applied.  In particular, the amount
> of time taken by c-inside-bracelist-p is ~29% out of the 42% that
> redisplay_internal is taking.  It will also account for a similar part
> of the garbage collection, giving around 2/3 of the time spent just in
> c-inside-bracelist-p.
>
> The patch ought virtually to eliminate that 2/3 of run time taken by
> that function, giving a speed increase of a factor of 3.
>
> Might it be that your Emacs is still loading native compiled files
> rather than the new .elc files?  Or something like that?
>
> > --
> > mvh/best regards Björn Lindqvist
>
> --
> Alan Mackenzie (Nuremberg, Germany).



-- 
mvh/best regards Björn Lindqvist