From owner-freebsd-hackers@FreeBSD.ORG Mon Jun 29 00:54:29 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 75C9A106567E for ; Mon, 29 Jun 2009 00:54:29 +0000 (UTC) (envelope-from nhoyle@hoyletech.com) Received: from mout.perfora.net (mout.perfora.net [74.208.4.194]) by mx1.freebsd.org (Postfix) with ESMTP id 3FDDE8FC18 for ; Mon, 29 Jun 2009 00:54:29 +0000 (UTC) (envelope-from nhoyle@hoyletech.com) Received: from [192.168.1.10] (pool-96-231-140-65.washdc.fios.verizon.net [96.231.140.65]) by mrelay.perfora.net (node=mrus1) with ESMTP (Nemesis) id 0MKpCa-1ML58Z1wua-000BsW; Sun, 28 Jun 2009 20:54:27 -0400 Message-ID: <4A4810BB.1010007@hoyletech.com> Date: Sun, 28 Jun 2009 20:54:19 -0400 From: Nathanael Hoyle User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: alc@freebsd.org References: <4A480760.50705@hoyletech.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V01U2FsdGVkX1+jiPym52ZTDjC1TcLHGqQVGtw3sYrT4a7Ixbo QeO992NOXSI2WrNnv/InAXh32raLZy6vyzErZv2s1Mhc8jIccU s6gr+41OSwgAl/cVPq3fPK5wp46+V8Q Cc: Wojciech Puchar , freebsd-hackers@freebsd.org Subject: Re: large pages (amd64) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Jun 2009 00:54:30 -0000 Alan Cox wrote: > On Sun, Jun 28, 2009 at 7:14 PM, Nathanael Hoyle wrote: > > >> Wojciech Puchar wrote: >> >> >>> i enabled >>> vm.pmap.pg_ps_enabled: 1 >>> >>> >>> could you please explain what exactly this values means? >>> because i don't understand why promotions-demotions!=mappings >>> >>> vm.pmap.pde.promotions: 2703 >>> vm.pmap.pde.p_failures: 6290 >>> vm.pmap.pde.mappings: 610 >>> vm.pmap.pde.demotions: 289 >>> >>> >>> >>> >>> other question - tried enabling it on my i386 laptop (256 megs ram), >>> always mappings==0, while promitions>demotions>0. >>> >>> certainly there are apps that could be put on big pages, gimp editing 40MB >>> bitmap for example >>> >>> >> Just to be clear, since you say i386 (I presume you mean architecture), I >> believe the Physical Address Extensions which allowed 2MB Page Size bit to >> be set was introduced with Pentium Pro. Processors prior to this were >> limited to standard 4KB pages. >> >> > > No. Many of those processors supported 4MB pages. > > Regards, > Alan > _______________________________________________ > Having been corrected by both you and Joerg (thank you!), I went back to re-verify my understanding. It appears that while I was slightly mixing PAE in with PSE, PSE support for 4MB pages was introduced 'silently' with the Pentium, and documented first with the Pentium Pro. I haven't found anything that points to earlier inclusion. Certainly the 80386 processor specifically, I am fairly confident would be limited to the 4KB pages. Agreed? Or are you aware of earlier usage than the Pentium for 4MB pages? Thanks, -Nathanael