Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!sharkey!atanasoff!hascall
From: hascall@atanasoff.cs.iastate.edu (John Hascall)
Newsgroups: comp.realtime
Subject: Re: Lightweight Tasks
Message-ID: <1271@atanasoff.cs.iastate.edu>
Date: 29 Jul 89 16:46:55 GMT
References: <2153@gmu90x.UUCP> <129300004@p.cs.uiuc.edu> <EYnoUGm00Vs8M9wZ0z@andrew.cmu.edu> <5323@ficc.uu.net>
Reply-To: hascall@atanasoff.cs.iastate.edu.UUCP (John Hascall)
Organization: Iowa State Univ. Computation Center
Lines: 20

In article <5323@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>In article <EYnoUGm00Vs8M9wZ0z@andrew.cmu.edu>, zs01+@andrew.cmu.edu (Zalman Stern) writes:
>> A lightweight task does not
>> have its own address space or other context (i.e. signal masks, uid,
>> file descriptor table etc...)
 
>Is this an observation or part of the definition. After all there need be
>no processing overhead for these other resources (i.e., a file descriptor
>does not require explicit action on a context switch), so there seems to
>be no advantage from leaving this much context out of a thread.

   But they do involve overhead during thread creation/deletion.

   Processes under VMS (for example) context switch quickly,
   but creation is quite lengthy.


John Hascall
ISU Comp Center