Date: Mon, 21 Nov 1994 19:14:47 -0500 (CDT)
From: Aaron Ucko <UCKO AT VAX1 DOT ROCKHURST DOT EDU>
Subject: Re: Program fast w/BC++, slow w/DJGPP
To: eliz AT is DOT elta DOT co DOT il
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Organization: Rockhurst College; Kansas City, MO

>This is a chess-playing program.  From what I've seen, it is quite
>CPU-bound; most of the time it just computes possible moves and checks
>their scores.  From time to time it writes short (~10 chars) messages
>to the screen (with cprintf()), and once every move it writes a line to
>a logfile.  Other than this, it doesn't do anything I can think of which
>would require a switch to real mode.  Does anybody know reasons other
>than file I/O which will cause a mode switch?

anything requiring a real-mode interrupt to be called (which includes all
I/O except for direct screen writes)

>actually performs the inlining.  I've run the profiler and found the
>histogram to be fairly flat: the most expensive function takes about
>15% of run time.  None of the library functions appear in the profile
>anywhere near the beginning, so the library is not the culprit.  The
Not necessarily; I believe profiling only sees how much time each function
spends in protected mode.

Two potential experiments:
1) Temporarily disable all unnecessary I/O
2) temporarily disable your CPU cache.

--- Aaron Ucko (ucko AT vax1 DOT rockhurst DOT edu; finger for PGP public key) -=- httyp!
-=*=-Just because you're paranoid doesn't mean they aren't out to get you.-=*=-
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