Re: Protected Objects And Many Processors

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Fri, 21 Jan 2011 19:09:34 +0100, Georg Bauhaus  
<rm.dash-bauhaus@futureapps.de> a écrit:
> The presence of shared data almost always triggers the idea
> of employing protected objects, since these avoid the overhead
> of task switching.  But availability of computing hardware seems
> to renders this a weaker argument.

Yes, The “Ada 95 Rationales” agree that efficiency is a key point:
http://www.adaic.org/resources/add_content/standards/95rat/rat95html/rat95-p2-9.html#1
Just that there is also semantic, protected objects are not just  
efficient, they also Protects (so their name) against simultaneous access  
to some data, i.e. one reading while another writing or one writing while  
another is writing too.

If you feel there may be a better solution, we first should now what that  
other solution could be (you did not say). You still need a  
synchronization mechanism, aren't you ?

I feel I did not understood the argument about the hardware. Would you  
like to be more explicit ?

> Will the program run just as well when written with only task
> objects if and when the number of available processors is
> sufficient, that is, C > N?
What was your criteria to decide one task here and there ? Use of tasking  
is directed by what the program is running, and we do not know anything  
about it. Here as well, tell more if you would like to.

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