Date: Thu, 05 Dec 2002 21:17:30 -0800 From: Peter Wemm <peter@wemm.org> To: "Ronald G. Minnich" <rminnich@lanl.gov> Cc: David Schultz <dschultz@uclink.Berkeley.EDU>, Gary Thorpe <gathorpe79@yahoo.com>, Terry Lambert <tlambert2@mindspring.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: maxusers and random system freezes Message-ID: <20021206051730.3F87E2A7EA@canning.wemm.org> In-Reply-To: <Pine.LNX.4.44.0212052043360.12734-100000@carotid.ccs.lanl.gov>
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"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
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