Date: Wed, 17 Jan 2001 13:53:27 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Cesar Rabak <csrabak AT uol DOT com DOT br>
cc: djgpp AT delorie DOT com
Subject: Re: Environment setting for running DJGPP in plain DOS in Win9x
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On Tue, 16 Jan 2001, Cesar Rabak wrote:

> Due the specific need to run in plain DOS to use the yamd, I noticed
> that a lot of programs run slower in this mode (Emacs seems to snail
> like the ole 486 era!).

I'm surprised you even succeeded to build and run Emacs with YAMD.
YAMD increases the memory footprint of a program considerably, and
Emacs is a very memory-intensive application.

How much memory does the system have physically installed?

I'm guessing that the fact that YAMD wraps malloc with code that makes
it allocate a whole page for each small memory chunk is one of the
reasons you see bad performance.  It makes the memory allocation
strategy, which assumes ``normal'' memory usage, work very far from
its optimum.

I don't remember whether YAMD involves generation ofg Page Faults when
valid addresses are accessed, but if it does, that might also cause
significant slow-down.

(Btw, if you find some problems in Emacs with YAMD, please report
them.)

> It seems to me that the main reason is the lack of a disk cache
> (SMARTDRV?).

Does the program page to disk a lot?  If not, SmartDrv is not your
problem (although installing it is definitely a good idea).

> Now, does anybody knows how to setup the windows 98 environment so that
> it runs the neeeded programs when booted in DOS and not in the `normal'
> mode?

Isn't there an AUTOEXEC.DOS file?

Anyway, there's a special tool in the Start->Programs->System Tools
dialog (don't remember its name) that allows you to edit system
files.  Also, the DOS box allows you to define an AUTOEXEC.BAT file
for switching to DOS Mode from Windows.