From owner-freebsd-hackers Sat Nov 15 23:42:38 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id XAA25133 for hackers-outgoing; Sat, 15 Nov 1997 23:42:38 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from dyson.iquest.net (dyson.iquest.net [198.70.144.127]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id XAA25128 for ; Sat, 15 Nov 1997 23:42:31 -0800 (PST) (envelope-from toor@dyson.iquest.net) Received: (from root@localhost) by dyson.iquest.net (8.8.7/8.8.5) id CAA12053; Sun, 16 Nov 1997 02:42:20 -0500 (EST) From: "John S. Dyson" Message-Id: <199711160742.CAA12053@dyson.iquest.net> Subject: Re: 256Meg In-Reply-To: from Alex at "Nov 15, 97 09:22:38 pm" To: garbanzo@hooked.net (Alex) Date: Sun, 16 Nov 1997 02:42:20 -0500 (EST) Cc: tom@sdf.com, hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL31 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk Alex said: > > > On Fri, 14 Nov 1997, Tom wrote: > > > > > On Fri, 14 Nov 1997, dennis wrote: > > > > > Is there a maximum that FreeBSD can support? > > > > > > Dennis > > > > > > What? Filesystems? RAM? Something else? > > > > RAM... no problem. I'm running two 256MB RAM servers now. > > Actually, there's a limit of 4GB or so of ram, on the 486 (if you call > tha ta limit ;-) ), and AFAIK the P5, P6 and PII and clones as well. > Physically, the limit is 36Bits on a P6. It would require some mods to the pmap layer, and maybe some enhancements to the upper level VM code. One disadvantage with the extended 3 level translation mode is that the PTE's become twice as large. I seriously doubt that we'll need that on a P6, but on future Slot1/Slot2 processors, we might find that 4GB is a real limit, and have to accomodate the modified PTD/PTE format. Imagine a processor that is perhaps 2X to 5X as fast as a P6, in a multiprocessor config -- that would appear to be able to use more than the typical upper end of 1GByte of memory, and even more than the normally addressable 4Gbytes. I haven't given this alot of thought yet, but these issues are probably going to be important in the medium-term future (approx 1yr.) -- John dyson@freebsd.org jdyson@nc.com