Re: process I/O is creepingly slow

[David Kastrup]

address@hidden (Kim F. Storm) writes:

> Do you think that the recent addition of process-adaptive-read-buffering
> is a satisfactory fix for the following bug report?
> 
> 
> David Kastrup <address@hidden> writes:
> 
> > Try the following:
> > 
> > M-x shell RET ls -l /etc | dd obs=1
> > 
> > The resulting process output crawls very very slow at first before
> > getting on-track.  Things like M-x compile, running AUCTeX and a lot
> > of other things are very negatively affected in their performance by
> > this process I/O bug.
> > 
> > In GNU Emacs 21.3.50.11 (i686-pc-linux-gnu)
> >  of 2003-03-27 on lola.goethe.zz
> > configured using `configure '--prefix=/usr/local/emacs-21' '--with-gtk''

I have just right now checked and compared the times in shell-mode
with Emacs-21.3, current CVS with process-adaptive-read-buffering,
XEmacs-21.4.12, xterm and Gnome terminal (similar geometry and font
size).  In order not to have Emacs at a disadvantage, I called it with
-unibyte.  The test command was

time hexdump -n 1000000 -v /dev/zero|dd obs=1

The times were:

Emacs-21.3: 2m15
Emacs-CVS: about 1m40
Gnome terminal: about 1m30
xterm: about 30s
XEmacs: about 30s

>From the visual appearance, the effect of
process-adaptive-read-buffering did not seem to set in: the cursor
basically appeared to move by character.  The visual appearance for
the good contestants (xterm and XEmacs) basically was a slower start
picking up speed later.

I have no clue why this would be the case.  Previous tests of adaptive
read buffering (although with an earlier version) turned out a vast
speed advantage at least in connection with the preview-latex package.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum