Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!ames!sun-barr!newstop!texsun!texbell!uhnix1!sugar!ficc!peter From: peter@ficc.uu.net (Peter da Silva) Newsgroups: comp.realtime Subject: Re: Lightweight Tasks Message-ID: <5393@ficc.uu.net> Date: 31 Jul 89 22:47:11 GMT References: <2153@gmu90x.UUCP> <129300004@p.cs.uiuc.edu> <1271@atanasoff.cs.iastate.edu> Organization: Xenix Support, FICC Lines: 28 In article <1271@atanasoff.cs.iastate.edu>, hascall@atanasoff.cs.iastate.edu (John Hascall) writes: > In article <5323@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes: > >In article , 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 [...], 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. Maybe, maybe not. If you set the thread control data structures up right the overhead could be limited to that of the actual resources used by the process. If you don't open any files, for example, no resources need be allocated to the process for files. > Processes under VMS (for example) context switch quickly, > but creation is quite lengthy. True, but a bit of a slippery-slope argument. Processes under VMS have a near-psychotic amount of context. -- Peter da Silva, Xenix Support, Ferranti International Controls Corporation. Business: peter@ficc.uu.net, +1 713 274 5180. | "The sentence I am now Personal: peter@sugar.hackercorp.com. `-_-' | writing is the sentence Quote: Have you hugged your wolf today? 'U` | you are now reading"