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Re: cc-mode fontification feels random
From: |
Alan Mackenzie |
Subject: |
Re: cc-mode fontification feels random |
Date: |
Sat, 12 Jun 2021 09:31:46 +0000 |
Hello, Eli.
On Sat, Jun 12, 2021 at 11:08:30 +0300, Eli Zaretskii wrote:
> > From: Daniel Colascione <dancol@dancol.org>
> > CC: <monnier@iro.umontreal.ca>, <rudalics@gmx.at>, <rms@gnu.org>,
> > <emacs-devel@gnu.org>
> > Date: Sat, 12 Jun 2021 01:00:22 -0700
> > > It is a problem given how much the current fast machines can do during
> > > that time. At 3 GHz, 30 msec of CPU time is equivalent to 100 million
> > > machine instructions.
> > And if you count electrons, the numbers are in the trillions. So what? Who
> > cares how many machine instructions it is? What matters is the latency.
> I'm saying that, given how much these machines can do in 30 msec, it
> doesn't sound right that we cannot refontify 35 lines of text with all
> that processing power. It tells me that our code is either very
> inefficient or does a lot of unnecessary processing (or both).
Or, due to the quirks of the CC Mode languages, it simply needs that
much processing to do an accurate job (or all three).
> Alan thought that the performance we have is acceptable. The numbers
> I mentioned would hopefully convince him otherwise.
I think the performance is fully acceptable to a normal user on a 3.4
GHz modern machine. If the processing power is available, why not make
use of it?
> > > We should either find a way of making this analysis faster, or give up
> > > on fontifying these two cases differently. It is IMO unacceptable
> > > that redisplay is slowed down so much by mode-specific fontifications.
As mentioned already, we have the facility of setting
font-lock-maximum-decoration to 2, which triples fontification speed.
This comes at the cost of accuracy. A lot of the bug reports I've
fielded over the years have been about fontification inaccuracies.
> > This is a great example of where incorrect fontification diminishes the
> > utility of syntax highlighting more generally. If I can't trust the color
> > of a symbol to distinguish a variable declaration from a type declaration,
> > why bother fontifying as either?
> I think we are saying the same, just in different words.
> Do you agree that slowing down redisplay so much due to fontification
> is unacceptable?
I think I would answer that on a modern machine (certainly from the last
5 years), using a normally optimised Emacs build, the fontification
isn't slowed down. On a somewhat slower machine, it could become
unacceptable, but that there are accpetable workarounds (setting
font-lock-maximum-decoration, or enabling fast-but-imprecise-scrolling,
or enabling deferred fontification). On a much slower machine, the
above doesn't hold, no.
I can't agree that we should expect C Mode to fontify with around the
same amount of processing as Emacs Lisp Mode. This isn't reasonable.
--
Alan Mackenzie (Nuremberg, Germany).
- Re: cc-mode fontification feels random, (continued)
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/12
- Re: cc-mode fontification feels random, Stefan Monnier, 2021/06/12
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/12
- Re: cc-mode fontification feels random, Alan Mackenzie, 2021/06/11
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/12
- Re: cc-mode fontification feels random, Daniel Colascione, 2021/06/12
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/12
- Re: cc-mode fontification feels random,
Alan Mackenzie <=
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/11
- Re: cc-mode fontification feels random, Alan Mackenzie, 2021/06/11
- Re: cc-mode fontification feels random, Óscar Fuentes, 2021/06/10
- Re: cc-mode fontification feels random, andrés ramírez, 2021/06/10
- Re: cc-mode fontification feels random, Stefan Monnier, 2021/06/10
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/11
- Re: cc-mode fontification feels random, Ergus, 2021/06/10
- Re: cc-mode fontification feels random, Óscar Fuentes, 2021/06/10
- Re: cc-mode fontification feels random, Ergus, 2021/06/10
- Re: cc-mode fontification feels random, Eli Zaretskii, 2021/06/10