From owner-freebsd-arch@FreeBSD.ORG Sat Jun 11 20:49:57 2011 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx2.freebsd.org (mx2.freebsd.org [IPv6:2001:4f8:fff6::35]) by hub.freebsd.org (Postfix) with ESMTP id E8F58106566C; Sat, 11 Jun 2011 20:49:57 +0000 (UTC) (envelope-from dougb@FreeBSD.org) Received: from [127.0.0.1] (hub.freebsd.org [IPv6:2001:4f8:fff6::36]) by mx2.freebsd.org (Postfix) with ESMTP id 24005157F87; Sat, 11 Jun 2011 20:49:47 +0000 (UTC) Message-ID: <4DF3D4EB.5030805@FreeBSD.org> Date: Sat, 11 Jun 2011 13:49:47 -0700 From: Doug Barton Organization: http://www.FreeBSD.org/ User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10 MIME-Version: 1.0 To: Kostik Belousov References: <4DF3B532.6020908@FreeBSD.org> <20110611201703.GO48734@deviant.kiev.zoral.com.ua> In-Reply-To: <20110611201703.GO48734@deviant.kiev.zoral.com.ua> X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Adrian Chadd , freebsd-arch@freebsd.org Subject: Re: [RFC] shipping kernels with default modules? 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: Sat, 11 Jun 2011 20:49:58 -0000 On 6/11/2011 1:17 PM, Kostik Belousov wrote: > On Sat, Jun 11, 2011 at 02:00:20PM -0600, Warner Losh wrote: >> >> On Jun 11, 2011, at 12:34 PM, Doug Barton wrote: >>> On 6/11/2011 2:21 AM, Adrian Chadd wrote: >>>> Hi guys, >>>> >>>> Has there been any further thought as of late about shipping kernels >>>> with modules only by default, rather than monolithic kernels? >>>> >>>> I tried this experiment a couple years ago and besides a little >>>> trickery with ACPI module loading, it worked out fine. >>>> >>>> Is there any reason we aren't doing this at the moment? Eg by having a >>>> default loader modules list populated from the kernel config file? >>> >>> Has anyone benchmarked monolithic vs. modular? I think that should be done before we move in this direction. >> >> I haven't noticed a difference, but I haven't done any specific benchmarking. > > There might be some measurable difference on i386, where we use dso for > modules. As a consequence, the overhead of GOT/PLT indirection, and, more > important, stolen %ebx on the register-starved architecture, may make > a difference. I doubt that any difference can be measured on amd64. And no one has ever been surprised that assumptions proved invalid in the light of actual testing? :) Theorizing on this point is of less-than-zero utility. Who is going to volunteer to do the actual benchmarking? Doug -- Nothin' ever doesn't change, but nothin' changes much. -- OK Go Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/