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From: sjr87@ecs.southampton.ac.uk (Simon Roberts)
Newsgroups: comp.os.minix
Subject: Messages and User Processes in 1.3
Message-ID: <6666.9102200948@jonson.ecs.soton.ac.uk>
Date: 20 Feb 91 09:48:01 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: sjr87@ecs.southampton.ac.uk
Organization: The University of Southampton, Hampshire, UK.
Lines: 28

I'm tinkering with an EGA graphics driver for 1.3 at the moment, and
the one thing which stands out is the relative slowness of the message
passing system when passing a message from me to the FS to ultimately
my EGA task in the kernel.

This is shown by the following fragment of code:

for (count=0;count<640;count+=2)
	line(count,0,count,349,count/2);

Here, line draws are effected by a separate message to the EGA
task via the FS, every time line() is called. Although the line draw
is a very fast routine (ie written in Assembler), the actual loop
takes a fair while because of the numerous messages.

Is there a way then that I can modify MINIX to pass the messages
straight to the Kernel, without having to go through the FS?

Any help gratefully received!!

Simon

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