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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.mel.connect.com.au!munnari.OZ.AU!news.ecn.uoknor.edu!news.wildstar.net!newsfeed.direct.ca!nntp.portal.ca!van-bc!unixg.ubc.ca!info.ucla.edu!agate!nickkral From: nickkral@america.CS.Berkeley.EDU (Nick Kralevich) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Linux vs. FreeBSD ... Date: 11 May 1996 08:07:30 GMT Organization: Electrical Engineering Computer Science Department, University of California at Berkeley Lines: 91 Message-ID: <4n1hs2$shg@agate.berkeley.edu> References: <3188C1E2.45AE@onramp.net> <4mr1pk$cdi@dyson.iquest.net> <4n0dhd$cff@agate.berkeley.edu> <31940EC3.61419F9C@lambert.org> NNTP-Posting-Host: america.cs.berkeley.edu In article <31940EC3.61419F9C@lambert.org>, Terry Lambert <terry@lambert.org> wrote: >] The reason why no one on the Linux side has written FreeBSD support >] is because, quite frankly, no one is that interested in it. There >] has been support for the BSD UFS to be added, but until someone >] finds a need to run *BSD binaries, it's not likely to happen. > >NetScape Commerce Server. 8-). Ya, I had thought about that, but I dismissed it because of the number of comparible freely available products that do the same thing. Examples include Apache-SSL-US and Apache-SSL, both of which are (arguably) compariable to the Netscape Commerce Server in that they both support encrypted traffic between two sites (they don't have the nifty GUI configuration utility, though). Of course, Apache-SSL works on both Linux and FreeBSD. And the Netscape Commerce server isn't officially supported by Netscape under FreeBSD. If your going to be paying $800+ for the commerce server, and not get any support, then that's your choice. >I have argued the danger of async writes at length in other >threads. People's inability to accept the implications of >"the completeness theorem" speaks only to their qualifications >as scientists. (oh no, not the sync vs async metadata argument again. Ahhhhh!!!) Perhaps that's the difference between scientists and engineers. This is just another example of the risk/rewards payoff. For volumes mounted async, there is approximately 10X increase in speed vs async for operations which do a lot of metadata update (such as untaring a file), with a minimal (some would say non-existant) increase in risk. There are lots of areas where this risk/reward payoff works. Examples include GCC with it's compiler flag "-ffast-math". As you've pointed out, FreeBSD supports async writes. As you didn't point out, Linux supports sync writes. Both options are available on both systems. FreeBSD comes with sync writes on by default, where Linux has async writes by default. I would argue that the Linux default is more flexable than the FreeBSD default. Under the default Linux setup, applications requiring sync access to the disk can always call "fsync()", "fdatasync()", or "msync()", or open the file with the "O_SYNC" option. However, with FreeBSD defaulting to sync updates, it is impossible to get async write behavior out of the filesystem. The Linux default is more flexable and offers higher performance at a minor (insignificant?) increase in risk. It's up to the individual user to make the choice to take or reject the risk vs reward of async updates. Lots of users take risks that are much worse than this, such as running without a UPS or not making backups. Both Linux and FreeBSD support sync and async updates, so there really isn't anything to argue about. >] Oh, one more quick question for FreeBSDers. Does FreeBSD support >] POSIX 1b realtime extentions yet? Is anyone working on it? This >] is a serious question. >Yes. Patches available on request to the author on the >FreeBSD RealTime list. Boy, you folks don't go out of your way to advertise this list, do you? The list is not searchable in the FreeBSD search page (http://www.freebsd.org/search.html), is not described in the FreeBSD handbook under "mailing lists" (http://www.freebsd.org/handbook/handbook251.html#459), nor is it described anywhere on the FreeBSD WWW site. But thank you for the information. I have an application I'm developing (a parallel MPEG encoder), that would benefit from the "aio_read()" and "aio_write()" syscalls, and I would like to see how (or if) FreeBSD impliments them. I've sent e-mail to the realtime list asking them to send me the location of the patches. Thanks for your help. >Does Linux support v10 of the POSIX threading, or only v4 of >1001.3b? This is a serious question. I'll do some research and get back to you on this. Take care, -- Nick Kralevich nickkral@cory.eecs.berkeley.edu