From owner-freebsd-stable@FreeBSD.ORG Fri Feb 27 16:43:15 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 33538106564A for ; Fri, 27 Feb 2009 16:43:15 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 037DD8FC17 for ; Fri, 27 Feb 2009 16:43:15 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (pool-98-109-39-197.nwrknj.fios.verizon.net [98.109.39.197]) by cyrus.watson.org (Postfix) with ESMTPSA id A16F946B59; Fri, 27 Feb 2009 11:43:14 -0500 (EST) Received: from localhost (john@localhost [127.0.0.1]) (authenticated bits=0) by server.baldwin.cx (8.14.3/8.14.3) with ESMTP id n1RGh8fT052712; Fri, 27 Feb 2009 11:43:08 -0500 (EST) (envelope-from jhb@freebsd.org) From: John Baldwin To: Michael Butler Date: Fri, 27 Feb 2009 11:42:59 -0500 User-Agent: KMail/1.9.7 References: <20090227130830.GI51952@rambler-co.ru> <200902271026.15796.jhb@freebsd.org> <49A812EC.8060408@protected-networks.net> In-Reply-To: <49A812EC.8060408@protected-networks.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902271143.00094.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (server.baldwin.cx [127.0.0.1]); Fri, 27 Feb 2009 11:43:08 -0500 (EST) X-Virus-Scanned: ClamAV 0.94.2/9054/Fri Feb 27 04:02:52 2009 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=4.2 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on server.baldwin.cx Cc: freebsd-stable@freebsd.org Subject: Re: 7.1-STABLE does not boot after recent superpage support MFC X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Feb 2009 16:43:15 -0000 On Friday 27 February 2009 11:21:00 am Michael Butler wrote: > John Baldwin wrote: > > On Friday 27 February 2009 8:08:30 am Igor Sysoev wrote: > > > >> And the message is cycled. The kernel does not boot despite > >> vm.pmap.pg_ps_enabled value. > > > > This should now be fixed, apologies for the breakage. :( > > What are the benefits and/or impacts of enabling this? > > Is there anything to be gained with respect to cache and/or TLB > utilization in allowing entry promotion through a reduced "footprint" or > similar? How much does this depend on architecture, say, e.g. Core-2 Duo > vs. Pentium? Yes there are gains due to what you mention, but it does depend on the specific processor and specifically the how it manages entries for large pages in its TLB (some processsors have separate TLB entries for large pages and have very few of them, others can store either a small or lage page in a single TLB slot, etc.). Alan knows far more of the details of this than I do. > I note that it is not enabled by default in -current either - just curious, Actually, it is enabled by default on amd64 in current. -- John Baldwin