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From: Adrian Knoth <adi@thur.de>
Newsgroups: comp.lang.ada
Subject: Re: Poor tasking performance
Date: 19 Jun 2004 23:51:58 GMT
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Robert I. Eachus <rieachus@comcast.net> wrote:

>> Is that normal? Only by adding one task which hangs in Get_Line
>> increases the load so much?
>> Environment is Linux 2.6.7 with Debian gcc-3.3 (unstable).
> First, let me say you are lucky to get working results with that 
> combination.

Ok, I can give gcc-cvs a try, let's see if it helps.

>   This is definitely an area where the underlying OS implementation of 
> reading from the console is going to account for most of the overhead.

I don't think the overhead is caused by Get_Line, but by tasks.

Get_Line can sleep until the OS wakes the thread up by a signal.
But I don't know if my runtime environment uses threads and
if they are wakeup-able ;)

> If you are using Get_Immediate in Text_IO, you could switch to line at a 
> time reading and see if that helps.  But I suspect that it won't--the OS 
> needs to poll the UART that buffers keyboard input at a certain rate to 
> avoid losing characters. 

Keyboard is interrupt driven.

I'll remove the Get_Line and see how much a serial program,
written as a task, will consume. If it's equal to the non-tasking
implementation I'll create a null-task to achieve some switching.


-- 
mail: adi@thur.de  	http://adi.thur.de	PGP: v2-key via keyserver

Natuerlich benutze ich Windows...$#��A NO CARRIER