Date: Sun, 13 Jul 2003 22:00:46 +0200
From: "Eli Zaretskii" <eliz AT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: djgpp AT delorie DOT com
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	(atlas_wang AT yahoo DOT com)
Subject: Re: Hardware Interrupt Latency in Protected Mode?
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> From: atlas_wang AT yahoo DOT com (Wang Yong)
> Newsgroups: comp.os.msdos.djgpp
> Date: 8 Jul 2003 09:21:45 -0700
> 
> Normally, the latency is
> less than 6 microseconds, which is really reasonable. However,
> sometimes (in 1 or 2 hours), a very large latency, 30 to 60
> microseconds, can be observed.

Sounds like some code in the BIOS.  BIOS is known to disable
interrupts for prolonged periods of time; I've seen similar problems
on occasion.  Disk I/O is the usual culprit.

Can you post the details of your system configuration (CONFIG.SYS,
AUTOEXEC.BAT, etc.)?

> And what steps should be strictly foloowed to
> restrain the latency in an acceptable range, such as < 10
> microseconds?

Unfortunately, I didn't find any work-around for this, except to
prevent the relevant BIOS code from running (which is not always
possible, alas).