From: postmaster AT fawlty8 DOT eng DOT monash DOT edu DOT au
Subject: Re: Compilation Speed... Thanks
To: djgpp AT sun DOT soe DOT clarkson DOT edu (DJGPP List)
Date: Wed, 27 Jul 1994 10:37:43 +1000 (EST)

Hi all,
	Thanks to those who replied, DJ and Roland.
> 
> > 	I noticed a large discrepancy in the compilation times of gcc
> > 	when running under normal dos and under the dos prompt in windows.
> > 	It runs very much faster under the windows dos prompt. I timed the
> > 	compilation of a c++ object file and while it took about 8 minutes
> > 	under dos, it was all over in about 30 seconds under windows !!
> > 	Any reason why this should be so ? Furthermore the dos shell was 
> > 	set to execute in the background.
> > 	Not that I mind the speed up :-) but I'd sure like to know why.
> > 	Thanks for any answers.
> 
> Run "go32" at both prompts and see how much memory it gives you.
> Chances are, there isn't enough memory in dos mode.

	That was exactly what's happening. I had used EMM386 as a device
	driver and thus in dos, I had only 256kB of VCPI memory while Windows
	provided about 2 meg of DPMI memory. I hadn't realised that go32 uses 
	VCPI memory ahead of extended memory.
	Disabling EMM386 made go32 use all 5 Meg of extended memory and thus
	improved compilation tremendously. 
	I had allocated most of my physical RAM as extended memory because
	I need to use Windows at work :-( Any reason why VCPI is used ahead
	of extended memory ? Is it faster ?
	Thanks once again for clearing things up.
> My record for compiling hello.c is 1.9 seconds.  This was at the dos
> prompt.
> 
> 
regards,
John

-- 
John Wong                   |        Tel : 905 5535
Elec. & Comp. Systems Eng.  |      email : wtwong AT fawlty7 DOT eng DOT monash DOT edu DOT au
Monash University           | 
Clayton, Victoria           |      "Do it or do it not, there is no try"
Australia                   |             - Yoda, TESB