Re: How can I predict which regions xdisp will present me for font-locking?

[Alan Mackenzie <acm@muc.de>]

Hello again, John.

On Tue, Mar 13, 2012 at 03:50:31PM -0400, John Yates wrote:
> On Mon, Mar 12, 2012 at 2:00 PM, Eli Zaretskii <eliz@gnu.org> wrote:

> > Can you give more quantitative description of the slowdown?  E.g., how
> > much time does it take to move the cursor by one character or one
> > line, or to insert or delete a single character?

> My work machine (4 year old technology):
> o Intel Core2 Duo E8400 (Wolfdale)
>   - dual core, 3GHz, 6MB shared L2, no L3
>   - 8GB DDr2 via separate Northbridge chip
> Barely tolerable, perceptible delay inserting characters

> Home machine (3 year old technology):
> o AMD Phenom II x4 945
>   - quad core, 3GHz, 512KB private L2, 6 MB shared L3
>   - 8GB DDR2 via low latency on-chip memory controller
> Really painful, at least a second to insert a single character.

This is in CC Mode, right?  It would be _really_ helpful to have a
description of which characters (e.g., comma, semicolon) are slow, and
what the buffer looks like in the vicinity of the slowness.  Is there a
dearth of semicolons and/or braces there?

For example, I'm struggling with getting the speed up on a 3355 line C++
macro.  Typing a comma towards the end of it is taking ~0.89 seconds on
my hardware (similarly specced to your home machine).

> The other thing I am noticing on both machine is that when I use
> keyboard repeat to "C-n" or arrow down I get scrolling behaves akin to
> an iPhone: after I release my key a large number of buffered input
> events continue the scrolling.

Is this in general, or in CC Mode?  In my mega-macro, I can't reproduce
this.

> > If you replace cc-mode Lisp files in v24 with those in v23, does the
> > problem go away?

> I am really not able to do so.  I do not build emacs from scratch.  I
> simply run the current state of Julien Danjou's emacs-snapshot on
> Ubuntu (11.04 at home, 11.10 at work).

I put in a considerable speed up to (long) macros on 1st March, and
another speed up on 2nd March.  Could it perhaps be that the snapshot you
use hasn't yet been updated for these?

> /john

-- 
Alan Mackenzie (Nuremberg, Germany).