Date: Sat, 27 Jan 2001 12:20:47 +1030 From: Greg Lehey <grog@lemis.com> To: Tim McMillen <timcm@umich.edu> Cc: Kenneth Wayne Culver <culverk@wam.umd.edu>, GLOBALLINK2001@aol.com, freebsd-questions@FreeBSD.ORG Subject: Re: FreeBSD-VS-Linux---Some Venting from Linux's side! Message-ID: <20010127122047.G12091@wantadilla.lemis.com> In-Reply-To: <0101251658280C.25766@tim.elnsng1.mi.home.com>; from timcm@umich.edu on Thu, Jan 25, 2001 at 04:58:28PM -0500 References: <Pine.GSO.4.21.0101251643310.13837-100000@rac4.wam.umd.edu> <0101251658280C.25766@tim.elnsng1.mi.home.com>
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On Thursday, 25 January 2001 at 16:58:28 -0500, Tim McMillen wrote: > On Thursday January 25, 2001 16:45, Kenneth Wayne Culver wrote: >>> i am on your side just wnated to know how much of FreeBSD >>> networking code is in 2.4? >> >> I'm not sure, but I think the BSD networking stuff has been in linux >> since 2.2, I think 2.4 got a lot of FreeBSD's VM stuff. I don't know >> how much of either is there, but I remember reading about it, and >> I've worked in both kernels before and have seen some pretty >> non-superficial similarities in both. > > You know, everybody says this, that Linux uses the FreeBSD tcp/ip > stack and other things, but no one seems to verify it. It's the first time I've heard it. It's wrong. > If they didn't actually use any of the code, but instead > rewrote similiar stuff, then they didn't really steal it. At that > point that's no different from any other code that gets shared > between the projects. Linux does borrow/import code from FreeBSD. Nobody's calling it stealing. I was at a Linux conference last week where two different developers (Dave Miller and Rik van Riel) presented work on the network stack and the VM system. Dave mentioned during his talk that his work was derived from David Greenman's sendfile() stuff, but it wasn't quite there yet. While he was talking I looked at the sendfile() sources on my laptop, and they're quite different from FreeBSDs. The differences in the underlying network implementation make it impractical to just copy code from FreeBSD. Rik mentioned FreeBSD in his summary at http://linux.conf.au/papers/#P02: Too Little, Too Slow: Linux 2.5 Memory Management Rik van Riel In Linux 2.5 virtual memory management will see some considerable changes. One of the main problems with the current Linux memory management is that sometimes we cannot make a proper distinction between pages which are in use and pages which can be evicted from memory to make room for new data. In order to improve that situation and make the VM subsystem more resilient against wildly variable VM loads, we will use ideas from various other operating systems to improve Linux memory management. The main page replacement routine will use the active, inactive and scavenge (cache) lists as found in FreeBSD. This mechanism maintains a balance between used and old memory pages so there will always be "proper" pages around to swap. In addition to this there will probably be things like dynamic and administrator settable RSS limits, anti hog code to prevent one user or process from hogging the machine and slowing down the rest of the machine and per-user memory accounting. As you'll see, they haven't exactly imported the whole VM system. That wouldn't be practical; even copying code from one BSD to another is difficult, and Linux is so different under the skin that it would extremely difficult. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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