Date: Mon, 16 Aug 1999 08:22:42 +0000 From: Marcel Moolenaar <marcel@scc.nl> To: current@FreeBSD.ORG Subject: Re: Linuxulator: emulation? [was: Q: Extending the sysctl MIB...] Message-ID: <37B7CA52.B6CEB30@scc.nl> References: <199908151724.KAA13658@dingo.cdrom.com>, <199908160432.WAA27186@harmony.village.org>
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Warner Losh wrote: > > In message <199908151724.KAA13658@dingo.cdrom.com> Mike Smith writes: > : We're staying away from the term "emulation" because it's being > : associated with things like the abominable 'lxrun' and virtual-machine > : emulators like VMware. > > Also, there is a perception that "emulation" is slower than native, > which isn't the case for the Linux ABI in FreeBSD. The Linuxulator adds overhead, which does make it slower than native. Take for example the overlaying of /compat/linux. File/dir access-bound applications (such as find) pay the penalty. Other areas of overhead are translations of bitmaps and/or structures. In general, the overhead is minimal, but nonetheless there's overhead and there're cases in which you can definitely see a performance drop as compared to native execution. I qualify the Linuxulator as an emulator. Although we are lucky to not have to emulate an architecture (see /usr/ports/emulators for examples) or a subset of an instruction set (option MATH_EMULATE for example), we do have to emulate an OS interface. The Linuxulator isn't a compatability thingy, because we're not that good an emulator. You cannot replace the one with the other and not see any side-effects. The emotional argument that as to why we stay away from the term "emulation" does not mean that the Linuxulator isn't an emulator, we're just calling it differently... anyway, my Euro 0.02 :-) -- Marcel Moolenaar mailto:marcel@scc.nl SCC Internetworking & Databases http://www.scc.nl/ Amsterdam, The Netherlands tel: +31 20 4200655 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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