X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
X-Trace-PostClient-IP: 68.147.177.20
From: Brian Inglis <Brian DOT Inglis AT SystematicSW DOT Invalid>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: why inportb and outportb are so time expensive ?
Organization: Systematic Software
Message-ID: <4c3nr0p78vv9arjeg7sqdj2apuu8nqov63@4ax.com>
References: <b3Aud.18735$Zk DOT 327000 AT twister2 DOT libero DOT it> <01c4df88$Blat.v2.2.2$3e1f4700 AT zahav DOT net DOT il> <gTDud.16862$Lg7 DOT 531795 AT twister1 DOT libero DOT it>
X-Newsreader: Forte Agent 1.93/32.576 English (American)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 26
Date: Sun, 12 Dec 2004 00:19:20 GMT
NNTP-Posting-Host: 24.71.223.147
X-Complaints-To: abuse AT shaw DOT ca
X-Trace: pd7tw1no 1102810760 24.71.223.147 (Sat, 11 Dec 2004 17:19:20 MST)
NNTP-Posting-Date: Sat, 11 Dec 2004 17:19:20 MST
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

On Sat, 11 Dec 2004 14:55:08 GMT in comp.os.msdos.djgpp, Carlo
<mail AT bo DOT uf> wrote:

>Eli Zaretskii wrote:
>> 
>> 
>> On what OS?
>> 
>> Also, can you give more details, like how much time each call to
>> inportb/outportb takes?
>My application runs on a dos machine (MS-Dos 6.0) with a i386sx 
>processor @ 33 Mhz clock, with cwsdpmi r5.
>One program loop takes about 1 mSec, 75% of this millisecond spent for 
>inportb and outportb (with an average of 30/40 calls to that functions). 
>Without any of these calls the program runs up to 10 times faster.

The instructions themselves probably aren't slow, but they talk to I/O
device interfaces, which talk to I/O devices, which can take a while.
How long do the I/O interface and device specifications say they will
take to respond to various commands or requests? 

-- 
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian DOT Inglis AT CSi DOT com 	(Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca)
    fake address		use address above to reply