Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759342Ab2HITOX (ORCPT ); Thu, 9 Aug 2012 15:14:23 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:52966 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755071Ab2HITOU (ORCPT ); Thu, 9 Aug 2012 15:14:20 -0400 Message-ID: <50240B77.2060204@linaro.org> Date: Thu, 09 Aug 2012 12:11:51 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: Michel Lespinasse CC: LKML , Andrew Morton , Android Kernel Team , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Dave Chinner , Neil Brown , Andrea Righi , "Aneesh Kumar K.V" , Mike Hommey , Jan Kara , KOSAKI Motohiro , Minchan Kim , "linux-mm@kvack.org" Subject: Re: [PATCH 1/5] [RFC] Add volatile range management code References: <1343447832-7182-1-git-send-email-john.stultz@linaro.org> <1343447832-7182-2-git-send-email-john.stultz@linaro.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12080919-7282-0000-0000-00000BD1BC6F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2112 Lines: 53 On 08/09/2012 02:46 AM, Michel Lespinasse wrote: > On Fri, Jul 27, 2012 at 8:57 PM, John Stultz wrote: >> v5: >> * Drop intervaltree for prio_tree usage per Michel & >> Dmitry's suggestions. > Actually, I believe the ranges you need to track are non-overlapping, correct ? Correct. Any overlapping range is coalesced. > If that is the case, a simple rbtree, sorted by start-of-range > address, would work best. > (I am trying to remove prio_tree users... :) Sigh. Sure. Although I've blown with the wind on a number of different approaches for storing the ranges. I'm not particularly passionate about it, but the continual conflicting suggestions are a slight frustration. :) >> + /* First, find any existing intervals that overlap */ >> + prio_tree_iter_init(&iter, root, start, end); > Note that prio tree iterations take intervals as [start; last] not [start; end[ > So if you want to stick with prio trees, you would have to use end-1 here. Thanks! I think I hit this off-by-one issue in my testing, but fixed it on the backend w/ : modify_range(&inode->i_data, start, end-1, &mark_nonvolatile_page); Clearly fixing it at the start instead of papering over it is better. >> + node = prio_tree_next(&iter); >> + while (node) { > I'm confused, I don't think you ever expect more than one range to > match, do you ??? So yea. If you already have two ranges (0-5),(10-15) and then add range (0-20) we need to coalesce the two existing ranges into the new one. > This is far from a complete code review, but I just wanted to point > out a couple details that jumped to me first. I am afraid I am missing > some of the background about how the feature is to be used to really > dig into the rest of the changes at this point :/ Well, I really appreciate any feedback here. thanks -john -- 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/