From owner-freebsd-arch@FreeBSD.ORG Sat Jun 11 20:49:26 2011 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 C3AC1106564A for ; Sat, 11 Jun 2011 20:49:26 +0000 (UTC) (envelope-from kmacybsd@gmail.com) Received: from mail-vx0-f182.google.com (mail-vx0-f182.google.com [209.85.220.182]) by mx1.freebsd.org (Postfix) with ESMTP id 614218FC18 for ; Sat, 11 Jun 2011 20:49:26 +0000 (UTC) Received: by vxc34 with SMTP id 34so4212821vxc.13 for ; Sat, 11 Jun 2011 13:49:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type :content-transfer-encoding; bh=fW+G/2qgiaqq8OdAazWg2UjmpNIqDIVnqV3tkrv9FQk=; b=B77NxgERzdi5TUURT1A0r8NCrPvZQrxyRZDgrCCPVgnXFTb7mOk9wZ7lFWz919ZROD xQGgbO9PaRSjj/FK8kWaN31aoAolelaMRzHzB2PctRrV5YdeEUcHSYiOQlrIgOGhmU8S 7KJmNWm/DZohu8zkdFyKd078n0P5TrzD8Igcw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type :content-transfer-encoding; b=cQv+9TWynLmh3Jeg7AzaUkTdPIZIM8WQkjMb35/PPrxQiYA8P/dG6RPE/tmNLytfNC rHkTvhomKsM9QOGca0Rr4G9NmoPAvrjRfwRasaQkSb7EXwJdnixnJZVuk6KbEgEsk/HT bZrl5xMLxLCiZsV7tn6iMFX+HpGRY3PJiImlw= MIME-Version: 1.0 Received: by 10.52.177.234 with SMTP id ct10mr4700503vdc.2.1307825365549; Sat, 11 Jun 2011 13:49:25 -0700 (PDT) Sender: kmacybsd@gmail.com Received: by 10.52.187.74 with HTTP; Sat, 11 Jun 2011 13:49:25 -0700 (PDT) In-Reply-To: <20110611204326.GA51320@zim.MIT.EDU> References: <20110611171834.GA38142@zim.MIT.EDU> <20110611204326.GA51320@zim.MIT.EDU> Date: Sat, 11 Jun 2011 22:49:25 +0200 X-Google-Sender-Auth: qM6z3YWTvIUsGOv99CPtvfyXXDM Message-ID: From: "K. Macy" To: mdf@freebsd.org, freebsd-arch@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: 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 20:49:26 -0000 >> Indeed, at $WORK we're trying to get shutdown -> restart under 2 >> minutes. =A0Several seconds of this is moving things *into* the kernel >> that need to be there (disk drivers), and everything else to a point >> in init where modules can be loaded in parallel, using the faster disk >> driver, rather than in serial with slow BIOS handlers. > > Have you found that drivers can be reliably loaded in parallel > these days? =A0I'm always waiting for timeouts on four card readers > and two optical drives, so that would be a big win for me. =A0IIRC, > nothing can happen in parallel during boot because the scheduler > is initialized very late in the process. =A0I'm not a device driver > person, but I imagine there might be other assumptions that might > get in the way as well. Although I imagine that many drivers silently benefit from being loaded serially, to the best of my knowledge there is nothing architecturally requiring this apart from the fact that the scheduler isn't started until everything else tied to initialization happens. The absence of any sort of preemption was a bit of a thorn in my side back when I was working on "xenbus", as the linux implementation relies on the use of multiple thread contexts. I don't know how much effort to date has been put in to making boot fast. Cheers, Kip