Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761600Ab3DBNbR (ORCPT ); Tue, 2 Apr 2013 09:31:17 -0400 Received: from mga03.intel.com ([143.182.124.21]:25082 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761289Ab3DBNbP (ORCPT ); Tue, 2 Apr 2013 09:31:15 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,393,1363158000"; d="scan'208";a="221869296" Message-ID: <515ADEDE.3050707@intel.com> Date: Tue, 02 Apr 2013 16:36:30 +0300 From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Chris Ball CC: Ulf Hansson , Sergey Yanovich , Greg Kroah-Hartman , Linus Walleij , Jaehoon Chung , Namjae Jeon , linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts References: <1363223183-3772-1-git-send-email-ynvich@gmail.com> <1363224194-7366-1-git-send-email-ynvich@gmail.com> <87620jmkoe.fsf@octavius.laptop.org> <87ppylf429.fsf@octavius.laptop.org> In-Reply-To: <87ppylf429.fsf@octavius.laptop.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1533 Lines: 43 On 27/03/13 13:57, Chris Ball wrote: > Hi, > > On Wed, Mar 27 2013, Ulf Hansson wrote: >> I noticed you merged this. I thought the idea was to use the rootwait >> or rootdelay? > > That's necessary before the patch, but it would be better if we didn't > have to pass rootwait, all else being equal. > >> Moreover, this patch will have bad impact on booting the kernel, since >> every host device that has scheduled a detect work from it's probe >> function will also wait for it to finish. Even if it is the boot >> device of not. If this is needed, I would prefer that a host cap is >> used. > > I see, you're worried about a performance regression where every boot > takes longer than it used to while MMC quiesces. That's fair. Do you > think you could tell me how much delay this adds to a boot for you, so > that we can consider whether the usability improvement is worth it? > > If the delay's significant, I agree with you and will revert this patch. On my system it is significant: Before the patch: [ 1.625623] VFS: Mounted root (ext4 filesystem) readonly on device 179:2. After the patch: [ 1.935851] VFS: Mounted root (ext4 filesystem) readonly on device 179:2. That is an addition of 310 ms which is 19% performance degradation. Please revert the patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/