From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxsystems.it ([79.7.78.67]:50658 "EHLO mail.linuxsystems.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbeERQhC (ORCPT ); Fri, 18 May 2018 12:37:02 -0400 From: =?iso-8859-1?Q?Niccol=F2_Belli?= To: David Sterba Cc: Subject: Re: Any chance to get snapshot-aware =?iso-8859-1?Q?defragmentation=3F?= Date: Fri, 18 May 2018 18:36:59 +0200 MIME-Version: 1.0 Message-ID: <99d57070-a1df-45ef-8f7e-df832bd7ad92@linuxsystems.it> In-Reply-To: <20180518162051.GS6649@twin.jikos.cz> References: <4428b2eb-796a-4c1b-8527-a05532436da4@linuxsystems.it> <20180518162051.GS6649@twin.jikos.cz> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On venerdì 18 maggio 2018 18:20:51 CEST, David Sterba wrote: > Josef started working on that in 2014 and did not finish it. The patches > can be still found in his tree. The problem is in excessive memory > consumption when there are many snapshots that need to be tracked during > the defragmentation, so there are measures to avoid OOM. There's > infrastructure ready for use (shrinkers), there are maybe some problems > but fundamentally is should work. > > I'd like to get the snapshot-aware working again too, we'd need to find > a volunteer to resume the work on the patchset. Yeah I know of Josef's work, but 4 years had passed since then without any news on this front. What I would really like to know is why nobody resumed his work: is it because it's impossible to implement snapshot-aware degram without excessive ram usage or is it simply because nobody is interested? Niccolò