>Date: Mon, 29 May 2000 14:32:36 +0200 (MET DST)
>I have a problem regarding running dosemu more than once at a time. I have
>a program which runs under DOS and is quite heavy on processor usage. I
>tried using it under Linux (Pentium II 366), one session runs OK but
>after 10 people connect over telnet and start it it slows down bigtime
>and it's impossible to continue to work.
Of course, if the program really needs a lot of CPU time, the
time can only shared between all users, and every of them gets
small part of it - looks like having a much slover machine.
But there is also something what sometimes causes a lot of the
CPU time to be wasted: when a program wants to read a keystroke
and does checks for a keystroke via BIOS call (INT 16h, AH=1)
while in idle loop. Such a program wasts a lot of CPU time when
it does nothing and waits for a command to be typed-in.
If the program used DOS call for the check, DOS would invoke an
INT 28h which after several repetitions (HogThreshold parameter)
would cause CPU to be released for other tasks; pure BIOS calls
do not activate it, and CPU time is wasted. I had the problem
with some program, and I wrote a small TSR for DOS which just
invokes INT 28h while servicing INT 16h with AH=1 - helped.
Jerzy
