From: Charles Sandmann <sandmann AT new-orleans DOT NeoSoft DOT com>
Subject: Re: program crashed only when profiled
To: dodger AT gcr DOT com (Roger Labbe)
Date: Mon, 6 Feb 1995 19:21:37 -0600 (CST)
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu

> A program I am developing crashes (locks up) only when profiled,
> i.e. compiled and linked with the -pg option. After running for
> several minutes I get a "Not ready writing drive C" error. The
> computer does not respond to the keyboard and I have to reboot. This
> crash only occurs when the program uses paged memory; when run with
> small data sets that don't require paged memory the program executes
> normally.

This is expected behavior (a known bug).  When you hook a HW interrupt
like the timer interrupt, you cannot page fault any of the memory you
access in the HW interrupt.  Since GO32 does not support locking pages,
you may page fault something during the profile.  This is expected to
be fixed in V2

> BTW, I am running with so little RAM specifically to test the performance
> of my algorithms in paged memory, so "buy more memory" is not a solution
> here.

As long as you don't hook HW interrupts, your code should be OK with V1.x
There is no way to profile elapsed time in a faulting program in V1.x, but
I hope this (and real mode time) would be available in V2.  We shall see,
I haven't beaten on the code real hard yet.  (Too many things to do).