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Re: X performance suffers under emacs 21.1.1


From: Richard Stallman
Subject: Re: X performance suffers under emacs 21.1.1
Date: Fri, 16 Nov 2001 23:32:21 -0700 (MST)

    After moving the emacs running gnus from an xterm to a vt ascii terminal
    I see "top" reporting 14.5MB usage instead of 30MB+.  That is enough to
    revitalize my memory usage on my 64MB system.

That is extremely strange.  For Emacs, an xterm is just an ASCII
terminal; Emacs does not treat it differently from a VT terminal.

Do you really mean that you ran Emacs talking directly to X (I.e., NOT
doing I/O through xterm)?  In that case, it is clear why the usage can
be different, but I am surprised it is that much.  I wonder if it is
consistent, or if you had just used more data in the tty session.  It
would be quite useful to make more systematic measurements for both
modes of operation.

I started the same Emacs executable on a tty and under X, the same
Emacs, and examined its size using `top' after typing
(while t nil) C-j.

On the tty, it used 4.8 meg.

On X, with an 80x40 or an 80x50 window, it used 7.4 meg.  With an
80x10 window it used 6.2 meg, and with an 80x30 window it used 6.3
meg.  It looks like display of the image in the splash screen is
responsible for 1.1 meg of additional memory usage.  (With 30 lines,
it is not displayed because there's no room.)  I got some confirmation
of this by using `-eval t' to inhibit display of the splash screen.
I got 6.3 meg even with 80x50.

Since splash.pbm is under 10k, I think the need for 1meg to display it
calls for investigation.  Would someone like to look at this?

Meanwhile, there is the question of where the other 1.4 meg goes.
Evidently it isn't the space for redisplay glyph data that uses it,
because extrapolation shows an 80x0 screen would use at least 6.1 meg.
Would someone like to look at this?



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