From owner-freebsd-hackers Thu Dec 5 21:17:44 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4B83437B401 for ; Thu, 5 Dec 2002 21:17:43 -0800 (PST) Received: from canning.wemm.org (canning.wemm.org [192.203.228.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id 032CF43EDE for ; Thu, 5 Dec 2002 21:17:39 -0800 (PST) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by canning.wemm.org (Postfix) with ESMTP id 3F87E2A7EA; Thu, 5 Dec 2002 21:17:30 -0800 (PST) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: "Ronald G. Minnich" Cc: David Schultz , Gary Thorpe , Terry Lambert , freebsd-hackers@FreeBSD.ORG Subject: Re: maxusers and random system freezes In-Reply-To: Date: Thu, 05 Dec 2002 21:17:30 -0800 From: Peter Wemm Message-Id: <20021206051730.3F87E2A7EA@canning.wemm.org> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG "Ronald G. Minnich" wrote: > On Thu, 5 Dec 2002, David Schultz wrote: > > > Linux used to do that, but AFAIK it doesn't anymore. > > Linux puts kvm at 0xc0000000, kernel at physical 0x100000, etc. There > was a time when you could address all of physical memory just by > direct-mapping the PTEs, since base of 0xc0000000 means KVM space > of 0x40000000. > > Those days are gone. Sort-of. They now use a milti-tiered memory pool system. The first block is direct mapped in using 4MB pages. That works out to something like 930MB or so. The balance (they have a 1GB KVA space too) is pageable to allow the kernel to access memory outside of the first 930MB (or whatever the exact amount is). What linux does that I find interesting is that they agressively *move* user pages in order to get best use of that 930MB pool. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message