Date: Mon, 08 Jun 1998 18:55:28 -0700 From: Studded <Studded@san.rr.com> To: Frank Pawlak <fpawlak@execpc.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: RTFM Message-ID: <357C9610.602218DB@san.rr.com> References: <356CA20F.1F47@clarityconnect.com> <980528041610.ZM1327@darkstar.connect.com> <35706214.119D02EB@san.rr.com> <980530212219.ZM4908@darkstar.connect.com>
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Sorry for the delay in response, both my business and personal lives have been rather hectic lately. :) Frank Pawlak wrote: > > Hi Doug, > > Thanks for your response. At the risk of embarrassment due to my ignorance, I > have to ask you to elaborate on a point you made. The Linux Kernel was > designed for 256 fd's, I am not clear on what this means. Could you please > define that in terms that a technically challenged person, me, could > understand? The way file descriptors, commonly referred to as 'fd's', were described to me I think is a good way to look at it.(I am vastly oversimplifying here, but I think it will help). The various processes on a unix system need fd's to interact with users, each other, etc. Each system has a fixed number of fd's, in freebsd this is determined at kernel compile time. If you think of each fd as a single sheet in a stack of paper, when you're out of paper the system can no longer interact with new users/processes without 'recycling' some sheets. In many ways Linux was designed to be a desktop unix.... something to play around with (again, oversimplifying). Therefore the system was hard wired to use only 256 fd's. More than enough for a desktop machine, not nearly enough for a serious server. There are kernel patches to increase that number to 1024, however our experience with linux is that other parts of the networking layer break down before the fd limit is reached. > If I could beg on your good graces a bit more, I am also under the impression > that the TCP/IP stack in Linux is inferior to that implemented in FreeBSD. Is > there any substance to that or is it now a non-issue? I am not intimately familiar with how it is implemented, but I can assure you that it's inferior based on our extensive testing. I hope this is helpful to you, Doug > On May 30, 12:46pm, Studded wrote: > > Subject: Re: RTFM > > Frank Pawlak wrote: > > > > > > Can anyone tell me where I can locate some accurate and current information > > > describing why FreeBSD can carry heavier server loads than Linux? > > > > Linux' kernel was designed for 256 fd's. It can be extended beyond that > > with some gymnastics however fundamentally the whole thing was not > > designed for "heavy server loads." The BSD networking layer has no such > > restrictions. > > > > We had a network consisting of almost all linux servers when I started > > on dalnet almost 3 years ago. Ours was the first machine to try FreeBSD > > and it wasn't very long before there weren't any linux boxes left. :) > > Now there are a few new linux machines but they are all in .eu where > > their client load is extremely small. > > > > Our experience with linux was that after a given period of time under > > load (that period varying with factors we were never able to clearly > > determine, but never more than 4 or 5 days) the networking layer would > > just give up and the server would become non-responsive over the network > > even though the machine was still up (active at the console). At the > > time there were several people in the linux world who were confirming > > that the failure was in the networking layer, including one of our > > programmers who contributes to linux. > > > > The word is that the 2.1 version of the linux kernel fixes "all" of the > > networking problems, however in our tests we have yet to get a linux 2.1 > > machine to hold more than 400 clients reliably, which is approximately > > where the 2.0 series failed as well. Of course, I have very little > > confidence in the person running the linux test, but I don't actually > > care that much either. :) > > > > Doug > > > > -- > > *** Chief Operations Officer, DALnet IRC network *** > > *** Proud designer and maintainer of one of the world's largest > > *** Internet Relay Chat servers with 5,328 simultaneous connections > > *** Try spider.dal.net on ports 6662-4 (Powered by FreeBSD) > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-questions" in the body of the message > >-- End of excerpt from Studded -- *** Chief Operations Officer, DALnet IRC network *** *** Proud designer and maintainer of one of the world's largest *** Internet Relay Chat servers with 5,328 simultaneous connections *** Try spider.dal.net on ports 6662-4 (Powered by FreeBSD) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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