Article View: comp.sys.powerpc
Article #1355Re: Macintosh tech stuff
From: Christopher Robato
Date: Sun, 20 Aug 1995 15:10
Date: Sun, 20 Aug 1995 15:10
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3348 bytes
Organization: Kuentos Communications Inc. Distribution: Jim Williams (williams@tiac.net) wrote: : crobato@kuentos.guam.net (Christopher Robato) wrote: : >: Presumably there are MacOS-specific issues I don't know about. : >: Perhaps apps diddle with system data structures as they set up : >: a co-operative task switch, and you don't want the pre-emptive : >: multitasker to interrupt them in the middle of it? : > : >You are close to it. : > : >Also, after they relinquish the CPU, they also expect to recieve a message : >from the OS, and certain data structures in the app and system are restored. : > : If this is the reason then some system designer must have their head : wedged. Wouldn't it be obvious to continue providing for the app's : volunary giving up time? This is certainly what I'm used to from an OS -- : if it isn't true in Unix I may find myself doing some Linux kernel hacking : sooner than I expected. : (Also, it would a bit of a kludge but it would be easy to fake giving : the app uninterrupted access to a system struct.) Exactly. You have to create a virtual enviroment that makes the coop app think it still has an entire, uninterrupted world all to itself. That's why in Copland, (and in Win-OS/2 and Win16 WOW emulation in NT) you have virtual worlds to dump coop apps there. If Gershwin wants to preempt every Mac coop app, the equivalent would be to run each Win16 app under a seperate session under OS/2 or NT. It will surely raise memory requirements, and in practice, only selectively rather than universally done. "Selectivity" implies usually regarding badly behaved, unstable, or nonyielding applications. Is it necessary? In general, I consider Mac apps to cooperatively behave better than Windows apps, and most Windows apps can be considered well behaved enough to be sharing sessions. Mac apps can all coop themselves in a single session under Copland quite happily thank you, so I really don't consider it to be quite that important an issue about Gerschwin preempting legacy Mac coop apps. By then, we can also expect that a sizable base of preemptable Copland apps would have sprung up. Rgds, Chris -- Rei Hino/Sailor Mars Ami Mizuno/Sailor Mercury Minako Aino/Sailor Venus Makoto Kino/Sailor Jupiter Haruka Tenoh/Sailor Uranus Michiru Kaioh/Sailor Neptune Setsuna Meioh/Sailor Pluto Usagi Tsukino/Sailor Moon *****crobato@kuentos.guam.net*****
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Newsgroups: comp.sys.powerpc,comp.os.linux.advocacy,comp.sys.mac.advocacy,comp.os.os2.advocacy,comp.sys.amiga.advocacy,comp.sys.intel Path: arc1-ca.pugleaf.net!swiss.ans.net!kuentos!crobato From: crobato@kuentos.guam.net (Christopher Robato) Subject: Re: Macintosh tech stuff Organization: Kuentos Communications Inc. Date: Sun, 20 Aug 1995 15:10:05 GMT Message-ID: <1995Aug20.151005.16216@kuentos.guam.net> Followup-To: comp.sys.powerpc,comp.os.linux.advocacy,comp.sys.mac.advocacy,comp.os.os2.advocacy,comp.sys.amiga.advocacy,comp.sys.intel,alt.2600,alt.destroy.microsoft X-Newsreader: TIN [version 1.2 PL2] References: <40t7qa$gap@nntp5.u.washington.edu> <415va3$g7n@goonsquad.spies.com> <4166oj$k9f@blackice.winternet.com> <wilcafe-2008950222390001@callaghan.coretech.com> <416q7e$6ik@bug.rahul.net> <1995Aug20.092448.13521@kuentos.guam.net> <417c7k$ndh@sundog.