From owner-freebsd-arch@FreeBSD.ORG Wed Aug 13 17:21:37 2008 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A0F591065673; Wed, 13 Aug 2008 17:21:37 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (bigknife-pt.tunnel.tserv9.chi1.ipv6.he.net [IPv6:2001:470:1f10:75::2]) by mx1.freebsd.org (Postfix) with ESMTP id EF7898FC14; Wed, 13 Aug 2008 17:21:36 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from localhost.corp.yahoo.com (john@localhost [IPv6:::1]) (authenticated bits=0) by server.baldwin.cx (8.14.2/8.14.2) with ESMTP id m7DHLNUi094237; Wed, 13 Aug 2008 13:21:30 -0400 (EDT) (envelope-from jhb@freebsd.org) From: John Baldwin To: Nathan Whitehorn Date: Wed, 13 Aug 2008 12:14:43 -0400 User-Agent: KMail/1.9.7 References: <48981C19.8060009@freebsd.org> <200808051024.27043.jhb@freebsd.org> <48A2E62A.9060604@freebsd.org> In-Reply-To: <48A2E62A.9060604@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200808131214.43326.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (server.baldwin.cx [IPv6:::1]); Wed, 13 Aug 2008 13:21:30 -0400 (EDT) X-Virus-Scanned: ClamAV 0.93.1/8026/Wed Aug 13 09:03:11 2008 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.6 required=4.2 tests=AWL,BAYES_00,NO_RELAYS autolearn=ham version=3.1.3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on server.baldwin.cx Cc: freebsd-arch@freebsd.org Subject: Re: UMA MD Small Allocator Runtime Switching X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Aug 2008 17:21:37 -0000 On Wednesday 13 August 2008 09:48:26 am Nathan Whitehorn wrote: > John Baldwin wrote: > > On Tuesday 05 August 2008 05:23:37 am Nathan Whitehorn wrote: > >> I'm working on the PowerPC G5 port right now, and have run into a > >> problem with the way the UMA small allocator works. On G3/G4 systems, > >> there is a direct physical->virtual mapping, and on G5s there isn't. All > >> of the infrastructure is in place to support both types of system with a > >> single kernel image, except that UMA_MD_SMALL_ALLOC must be switched > >> on/off at runtime. > >> > >> One solution is to put if (direct_map) use_nonsmall_case() into the MD > >> small_alloc/free() routines and define UMA_MD_SMALL_ALLOC everywhere. > >> This works well, except that the MI UMA code then sets booted = 1 too > >> early in the boot process, before the kmem_alloc*() routines are available. > >> > >> Basically, I need to find a way have an MD UMA allocator without the MI > >> UMA code assuming anything about how it works internally. Maybe adding a > >> UMA_MD_ALLOC_LATE define to prevent setting booted=1 early on? > >> -Nathan > > > > Have you considered creating an artificial direct map region in the address > > space on the G5? Some of the other 64-bit ports (amd64 and sparc64) do this > > to gain the benefits of the direct map even though it isn't a mandated part > > of the architecture like it is on some other platforms (alpha and mips). > > I thought about it, but we can only use 4K pages on the G5 so this would > put a large amount of pressure on the page table. IBM removed the block > translation mechanism from the G5 and the CPU's superpage support is not > available in the 32-bit compatibility mode under which we currently run. Hmm, I didn't know you weren't running in full 64-bit mode. Is that a property of the G5 CPU that it only supports the 32-bit compat mode with 64-bit extensions? -- John Baldwin