Date: Sun, 3 Apr 1994 13:18:19 +0200
From: terra AT diku DOT dk
To: stevev AT miser DOT uoregon DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: DJGPP Speed

   Date: Wed, 30 Mar 94 09:57:06 PST
   From: stevev AT miser DOT uoregon DOT edu (Steve VanDevender)

   terra AT diku DOT dk writes:

    > I think we could improve the speed of all djgpp programs a lot by making
    > structures and procedures in go32 aligned properly.  As it is now, every-
    > thing is byte aligned and should be:

   Aligning those structures might slightly improve the speed of DOS
   calls through go32 but I doubt this would make much visible
   difference.

Actually, we would see a speed improvement on all interrupts occuring
while the processor is in protected mode, e.g., the timer interrupt
and the page fault exception.  At least two task switches are involved
with every such interrupt.

I did some optimizations on a crypt(1) implementation once and found
that proper alignment could speed up things by 20%.  This particular
program referenced memory a *lot* of the time (90% of all instructions
accessed double words) so 20% is probably an upper bound.

What aligning would amount to in the gcc case is rather difficult to say
in advance, though.  I would only expect a few percent.  Since it is 
rather easy to do, I figure it would be worth the while.

Morten Welinder
terra AT diku DOT dk