Date: Wed, 24 Apr 2002 03:27:44 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: David Schultz <dschultz@uclink.Berkeley.EDU> Cc: kalts@estpak.ee, "Marc G. Fournier" <scrappy@hub.org>, freebsd-current@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: FreeBSD 4.5-STABLE not easily scalable to large servers ... ? Message-ID: <3CC688A0.316ED250@mindspring.com> References: <3CC4C683.F9AEF14E@mindspring.com> <20020423092909.N1721-100000@mail1.hub.org> <20020423184534.GA30212@myhakas.estpak.ee> <3CC5B52B.49A5A719@mindspring.com> <20020423220408.C3593@HAL9000.wox.org>
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David Schultz wrote: > Thus spake Terry Lambert <tlambert2@mindspring.com>: > > Writing a useful (non-"fluff") technical book, optimistically, > > takes 2080 hours ... or 40 hours per week for 52 weeks... a man > > year. > > > > By the time you are done, the book is a year out of date, and > > even if you worked really hard and kept it up to date (e.g. you > > had 4 authors and spent only 6 months of wall time on the book), > > the shelf life on the book is still pretty short. > > Although it would be unreasonable to comprehensively document the > kernel internals and expect the details to remain valid for a year, > there is a great deal of lasting information that could be conveyed. > For example, Kirk's 4.[34]BSD books cover obsolete systems, and yet > much of what they say applies equally well to recent versions of > FreeBSD. These are general OS architecture books by a noted authority on OS architecture. That's a barrier to entry for other authors, as the intrinsic value in the information is not constrained to the direct subject of the work. 8-). Kirk is supposedly working on a similar book for FreeBSD, release date indeterminate. In any case, this doesn't resolve the issue of "Where do I go to do XXX to version YYY, without having to learn everything there is to know about YYY?". > It's true that the specific question ``How do I change my KVA size?'' > might have different answers at different times, but I doubt that the > ideas behind an answer have all been invented in the last few months. > Even things like PAE, used by the Linux 2.4 kernel, remind me of how > DOS dealt with the 1 MB memory limit. The PAE is the thing that Peter was reportedly working on in order to break the 4G barrier on machines capable of accessing up to 16G of RAM using bank selection. I didn't mention it by name, since the general principle is also applicable to the Alpha, which has a current limit of 2G because of DMA barrier and other constraints. While it's true that the ideas behind the answer remain the same... the ideas behind the answer are already published in the books I've already referenced in the context of this thread. If people were content to discover implementation details based on a working knowledge of general principles, then this thread would never have occurred in the first place. It's my opinion that people are wanting to do more in depth things to the operating system, and that there is a latency barrier in the way of them doing this. My participation in this discussion, and in particular, with regard to the publication of thorough and useful documentation, has really been around this point. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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