Re: gnat: time-slicing

[aaro@iki.fi (Aaro Koskinen)]

lutz@iks-jena.de (Lutz Donnerhacke) writes:
> * Jan Prazak wrote:
> >The tutorial mentions, that
> >
> >ab
> >
> >ab
> >
> >can be produced even on systems with only one CPU, depending on the
> >compiler.
> 
> First you need a OS able to perform a task switch while performing system IO.
> Most multitasking OS do not do this. While performing a system call, this
> call can not interrupted by normal tasking.

It's also a question of I/O buffering. I'm not sure if GNAT libraries
use libc for I/O in Linux, but if they do, then the default buffering
mode for stdout is "line buffering", i.e. each line is written using a
single system call. It is possible to turn I/O buffering off, which
results in a system call for each character - and this would allow a
task switch between each character.

A.

-- 
Aaro Koskinen
E-mail: aaro@iki.fi            "I'm the ocean, I'm the giant undertow."
http://www.iki.fi/aaro