Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!cbmvax!jesup
From: jesup@cbmvax.UUCP (Randell Jesup)
Newsgroups: comp.sw.components
Subject: Re: Inheritance vs. component efficiency
Message-ID: <7760@cbmvax.UUCP>
Date: 27 Aug 89 04:36:16 GMT
References: <130200005@p.cs.uiuc.edu> <6254@hubcap.clemson.edu>
Reply-To: jesup@cbmvax.UUCP (Randell Jesup)
Organization: Commodore Technology, West Chester, PA
Lines: 22

In article <6254@hubcap.clemson.edu> billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu writes:
>    Ralph also assumes that task creation
>   will be a high-overhead situation; however, this is a characteristic
>   of certain *operating systems*, not a characteristic of Ada.  Work is
>   also being done on "Ada engines", systems which are specifically
>   designed to, among other things, provide the support for lightweight 
>   processes that is appropriate for an Ada environment.  

	Such systems already exist, though they don't all have Ada compilers
for them (yet).  For example, the Amiga OS is based on lightweight tasks:
a task switch on a 7.16Mhz 68000 machine costs only 400us.  Creating tasks
takes only a few milliseconds, most of that stack-allocation time (rough
estimate off the top of my head).  Of course, these things go MUCH faster on
14-Mhz '020's or 25-Mhz '030's.

	MACH also has lightwieght thread support (though MACH threads are
'heavier' than Amiga tasks, in general.)

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"