Re: [levoy@cs.stanford.edu: Poor performance over DSL link]

[Richard Stallman <rms@gnu.org>]

Here is the old message.

From: "Kim F. Storm" <storm@filanet.dk>
To: rms@gnu.org
CC: miles@gnu.org, storm@filanet.dk, emacs-pretest-bug@gnu.org
In-reply-to: <200012121602.JAA23121@wijiji.santafe.edu> (message from Richard
	Stallman on Tue, 12 Dec 2000 09:02:15 -0700 (MST))
Subject: Re: Performance running emacs with X over 64 kbps link.
References: <200012072142.eB7LgkF24504@mail.filanet.dk>
	<200012081646.JAA14693@wijiji.santafe.edu>
	<200012110930.eBB9UrF06342@mail.filanet.dk>
	<200012111700.KAA21073@wijiji.santafe.edu> <buoofyizcn6.fsf@mcspd15.ucom.lsi.nec.co.jp> <200012121602.JAA23121@wijiji.santafe.edu>
Content-Type: text
Content-Length: 1997

> Date: Tue, 12 Dec 2000 09:02:15 -0700 (MST)
> From: Richard Stallman <rms@gnu.org>
> 
>     Optimizing emacs' wire efficiency when using the X protocol may be
>     interesting but there are certainly many more important things to do...
> 
> I agree it is not of first-level importance.
> And it makes sense to tell people in this situation
> "Turn off features A, B and C for faster operation."
> 
> Still, it does matter to some extent.  It could be worth figuring out
> which features to advise them to turn off, and if something is
> gratuitously slow in how it uses X, speeding it up would be good for
> everyone.

I have been digging a little further into this issue.
I was wondering why emacs was so slow during start-up (+ 1 minute)
especially the noticeable delay between messages like
	Loading some-file.elc...
and
	Loading some-file.elc...done

It seemed that every package that uses 'defface' or 
actively manipulates the x-frame parameters are subject
to a several seconds load time.

I then used ethereal to trace on ppp0, and it turns out that emacs
is doing multiple calls to XListFonts(), XLookupColor() and
XAllocColor() - for the same font pattern and colors...

Since there is obviously no caching of the information read
from the X-server, it repeats those requests... which in
total causes a significant delay in emacs startup.

Totally, emacs exchanges ~1800 X11 (and TCP) packets
with the X-server before it is ready for use...  after some
75 seconds.  [this is when I delay the loading of .emacs
until the initial frame is properly displayed; without
that hack, loading emacs takes twice as long -- see my
previuos mails explaining this].

I don't know whether it is legal to cache any of this 
information, but doing so would probably make a significant
improvement in start-up time over slow links - any maybe
a small improvement in general.

-- 
Kim F. Storm  <storm@filanet.dk>      http://www.filanet.dk
Filanet Europe A/S    Herlev Hovedgade 82C,1 DK-2730 Herlev