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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.mel.connect.com.au!news.syd.connect.com.au!phaedrus.kralizec.net.au!news.mel.aone.net.au!grumpy.fl.net.au!news.webspan.net!ix.netcom.com!super.zippo.com!zdc!zippo!news From: wexler@inter.net.il (Enoch Wexler) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Embedded FreeBSD Date: Tue, 21 Jan 1997 11:03:55 GMT Organization: Wexler Computer Systems Development Ltd. Lines: 17 Message-ID: <32e4a295.4103196@news.zippo.com> References: <32B744C0.2DA9@wdc.net> <5bdbd0$uih@news.aus.world.net> <32DA62A7.A91@onramp.net> <5be62a$14b@qnx.com> <5bqs4v$oar@uriah.heep.sax.de> <5c08m3$dvk@qnx.com> <5c14ih$7nn@uriah.heep.sax.de> Reply-To: wexler@inter.net.il NNTP-Posting-Host: rg-f30.access.net.il X-Newsreader: Forte Free Agent 1.1/32.230 Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:34401 On 21 Jan 1997 01:02:09 GMT, j@uriah.heep.sax.de (J Wunsch) wrote: >doug@qnx.com (Doug Santry) wrote: > >> The kernel is riddled with splhigh() calls. I wouldn't trust a device >> that needs attention in under 2 microseconds on a Unix system. QNX >> can guarantee it on a 200 MHz pentium. That is the worst case interrupt >> latency. > >Sure, 2 µs is certainly out of the question with a Unix kernel. 20 µs >probably not. Hey!, my old CP/M BIOS had to pick up one byte after >each 16 µs from the FDC -- without DMA. :-) > >The biggest problem is to keep the splhigh() times short. Ask the hardware engineer to do a better job and relax that 2 µs constraint... Enoch.