From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:46657 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214AbcI0SuW (ORCPT ); Tue, 27 Sep 2016 14:50:22 -0400 Date: Tue, 27 Sep 2016 11:50:21 -0700 From: Christoph Hellwig Subject: Re: [PATCH 58/71] xfs: garbage collect old cowextsz reservations Message-ID: <20160927185021.GA8623@infradead.org> References: <147216791538.867.12413509832420924168.stgit@birch.djwong.org> <147216829394.867.16281333542262043955.stgit@birch.djwong.org> <20160924194234.GA1878@infradead.org> <20160926215209.GE14092@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160926215209.GE14092@birch.djwong.org> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: Christoph Hellwig , david@fromorbit.com, linux-xfs@vger.kernel.org, xfs@oss.sgi.com On Mon, Sep 26, 2016 at 02:52:09PM -0700, Darrick J. Wong wrote: > The two functions /could/ be merged but I'm hesitant to combine them > because they run as different workqueue items. > > Setting speculative_cow_prealloc_lifetime to a (much) higher value than > speculative_prealloc_lifetime has been useful for combatting CoW > fragmentation on VM hosts where the VMs experience bursty write > behaviors and we can keep the utilization ratios low enough that we > don't start to run out of space. IOWs, it benefits us to keep the CoW > fork reservations around for as long as we can unless we run out of > blocks or hit inode reclaim. Ok, so there is a good use case for it. It just felt to me like there was a little bit too much duplication, that's why I asked.