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Newsgroups: comp.unix.bsd.freebsd.misc Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!metro!munnari.OZ.AU!news.hawaii.edu!ames!enews.sgi.com!news.mathworks.com!newsfeed.internetmci.com!in2.uu.net!news.thepoint.net!news1!not-for-mail From: root@dyson.iquest.net (John S. Dyson) Subject: Re: FreeBSD vs. Linux X-Nntp-Posting-Host: dyson.iquest.net Message-ID: <4o7gsh$8ge@dyson.iquest.net> Sender: news@iquest.net (News Admin) Organization: John S. Dyson's Machine References: <318FA7CB.8D8@hkstar.com> <31A2A83D.67A89A35@lambert.org> <4o1om8$156@dyson.iquest.net> <4o4lel$mu3@Mars.mcs.com> Date: Sat, 25 May 1996 17:43:45 GMT Lines: 62 In article <4o4lel$mu3@Mars.mcs.com>, Leslie Mikesell <les@MCS.COM> wrote: >In article <4o1om8$156@dyson.iquest.net>, >John S. Dyson <root@dyson.iquest.net> wrote: > >>>] and networking speed seems reasonable. How would freeBSD be >>>] better if I don't need greater-than-ethernet speeds? >>> >>>Depends onthe loading characteristics for the machine, *exactly* >>>what you plan to use it for, etc.. >>> >>Following on to Terry's comment: >> >>Since the FreeBSD networking uses less CPU, it means that more is >>available for you. Of course, if you need very little bandwidth, then >>it isn't important. > >But can you quantify that a bit? I don't think my machines are >ever CPU bound to a point where I would notice this, but perhaps >it is just because I have cheap disks and network cards. > If your systems are not saturating your networks, then the slower networking perf on Linux won't make much difference. Slow network cards probably overshadow most of the os overhead of either FreeBSD, Linux or NetBSD. At 100% 10Mbps ethernet, an NE2000 takes 50% of your CPU for ISA bus overhead, and an SMC shared memory card takes about 25% of your CPU for ISA bus overhead. These numbers are constant if you are using a 486/66 or Pentium-Pro!!! (since the bus timing is pretty much the same.) Things get more interesting (the OS becomes more critical) when you use efficient PCI based ethernet adapters or 100Mbps networks. There is a gross misconception that the mbuf based networking code on *BSD is inefficient. Quite the contrary, copies are minimized at least on the recent *BSD releases. Mbuf clusters are used much more intelligently than they used to be. (The mbuf code might be ugly to the casual observer, but there are individuals who like it :-)). > >on a Linux machine to make it match freeBSD performance, at least >as measured from the other end of a network connection? Would >it take a 120 vs. 100 Mhz Pentium, additional RAM, more efficient >network cards or...? > I would suggest on stable Linux releases as of today that Linux is about 1/2 as fast on TCP transfers (internally) as released versions of FreeBSD (per lmbench and friends.) I have seen results using real ethernet cards that are more striking. But, it isn't always important since both systems can easily saturate a T1 (< 1/8 of an ethernet in each direction.) On locally connected networks, or on well connected systems, you have to decide how important networking perf is to you. I suggest comparing the systems under your real loads to see which works best, if you are interested. It takes me about 1Hr at most to install a FreeBSD system from scratch (I usually make partitioning errors, so it takes me longer than some people, others might take a few hours if there are unexpected hardware configuration issues.) Regarding improving your performance, the simplest thing that you can do with the least overhead or worry is to upgrade from an ISA interfaced ethernet card to say, a PCI DEC-chip based ethernet card like the SMC Etherpower? series. You won't have to change your OS, and you'll gain 20%-40% of your CPU back, at full bandwidth (if you can achieve that :-))!!! John