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From: rooij@bashful.isp.cft.philips.nl (Guido van Rooij)
Subject: Re: V86 mode & the BIOS (was Need advice: Which OS to port to?)
Message-ID: <1993Aug12.110032.16307@cnplss5.cnps.philips.nl>
Sender: news@cnplss5.cnps.philips.nl (USENET News System)
Organization: Philips Communications & Processing Services, Eindhoven
References: <3390@vall.dsv.su.se> <CB11pL.D12@imag.fr> <107181@hydra.gatech.EDU> <1993Aug4.073826.24956@fcom.cc.utah.edu> <107725@hydra.gatech.EDU> <245jrfINNrc0@bonnie.tcd-dresden.de> <108457@hydra.gatech.EDU>
Date: Thu, 12 Aug 1993 11:00:32 GMT
Lines: 20
gt8134b@prism.gatech.EDU (Howlin' Bob) writes:
>As for slow task switching, the 386 doesn't access the I/O permissions
>bitmap until an I/O instruction occurs. The size of the bitmap has
>no effect on task switching performance.
The reason this was brought up is the fact that on task switching you
also need somehow to get the io permission bitmap in the TSS. Since
386bsd does not use the builtin taskswitching of the 386, theis bitmap
has to be memcpy'd into the TSS, resullting in slow task switches.
>Linux has rather zippy task switching, in my opinion.
>--
>Robert Sanders
>Georgia Institute of Technology, Atlanta Georgia, 30332
>uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt8134b
>Internet: gt8134b@prism.gatech.edu
-Guido