From owner-freebsd-arch Sat Oct 12 5:53: 6 2002 Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 54F6F37B401 for ; Sat, 12 Oct 2002 05:53:05 -0700 (PDT) Received: from phoenix.infradead.org (carisma.slowglass.com [195.224.96.167]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4AF0543EAF for ; Sat, 12 Oct 2002 05:53:04 -0700 (PDT) (envelope-from hch@infradead.org) Received: from hch by phoenix.infradead.org with local (Exim 4.10) id 180Ll7-0004Jk-00; Sat, 12 Oct 2002 13:52:45 +0100 Date: Sat, 12 Oct 2002 13:52:45 +0100 From: Christoph Hellwig To: Wes Peters Cc: Matthew Dillon , "Vladimir B. Grebenschikov" , Nate Lawson , arch@FreeBSD.ORG Subject: Re: Database indexes and ram (was Re: using mem above 4Gb was:swapon some regular file) Message-ID: <20021012135245.A16453@infradead.org> References: <1034105993.913.1.camel@vbook.express.ru> <200210082015.g98KFFrq084625@apollo.backplane.com> <1034109053.913.7.camel@vbook.express.ru> <200210082051.g98KpjU1084793@apollo.backplane.com> <3DA4C271.37AACAA3@softweyr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <3DA4C271.37AACAA3@softweyr.com>; from wes@softweyr.com on Wed, Oct 09, 2002 at 04:57:37PM -0700 Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Wed, Oct 09, 2002 at 04:57:37PM -0700, Wes Peters wrote: > Linux solved this problem by refusing to do it. The candidates for DMA > transfers include skbufs and buffers from the disk buffer pool, both of > which are allocated from the lowest 4GB of physical ram when using PAE > mode. Umm, Linux _does_ DMA into any memory if the NIC/HBA/whatever supports it. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message