From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q5BGL9GW113974 for ; Mon, 11 Jun 2012 11:21:09 -0500 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id gcDCAhmbsNEMI6mb for ; Mon, 11 Jun 2012 09:21:08 -0700 (PDT) Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q5BGL7da029882 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 11 Jun 2012 12:21:07 -0400 Received: from andromeda.usersys.redhat.com (vpn-9-5.rdu.redhat.com [10.11.9.5]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q5BGL39I019321 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Mon, 11 Jun 2012 12:21:06 -0400 Date: Mon, 11 Jun 2012 13:21:03 -0300 From: Carlos Maiolino Subject: Re: block sizes > 4K ?? possible w/large page support? Message-ID: <20120611162102.GB18432@andromeda.usersys.redhat.com> References: <4FD5643F.5070801@tlinx.org> <20120611132932.GA18432@andromeda.usersys.redhat.com> <4FD606C1.1070103@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4FD606C1.1070103@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com > > The maximum block size of a XFS filesystem is 64kiB. But in linux it's limited > > to the PAGE_SIZE value. > > Correct. > > > so, on x86 architectures, the maximum block size is > > 4kiB. > > Not entirely correct. Since ~1996, 16 years ago, PPro and higher 32bit > CPUs with PSE/PSE36 support pages of 4MB, or 2MB with PAE enabled. > I know we can use hugepages with these sizes, but didn't know we can use this as common usage. I tried to look at MM code and didn't find anything which would make PAGE_SIZE greater than 4096 (at least in x86), but well, I'm not a MM developer too. > x86-64 CPUs in long mode also support a 2MB page size. But the problem > of internal fragmentation may outweigh the TLB and other benefits of > these very large pages. I'm not an MM dev so I can't elaborate further. > There may be other issues. > > > although it could benefit from a 16kiB page size, you'll need to be running an > > operating system which supports this page size value. > > And AFAIK the kernel MM team doesn't have x86 2MB pages on their radar. > Or do they? No clue, I'm not a MM developer too =/ maybe I can be someday :D -- --Carlos _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs