From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outrelay06.libero.it ([212.52.84.110]:51699 "EHLO outrelay06.libero.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750905AbaFPQ3A (ORCPT ); Mon, 16 Jun 2014 12:29:00 -0400 Message-ID: <539F1C35.6060302@inwind.it> Date: Mon, 16 Jun 2014 18:32:53 +0200 From: Goffredo Baroncelli Reply-To: kreijack@inwind.it MIME-Version: 1.0 To: Lennart Poettering CC: Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org, systemd-devel@lists.freedesktop.org Subject: Re: [systemd-devel] Slow startup of systemd-journal on BTRFS References: <1346098950.2730051402571606829.JavaMail.defaultUser@defaultHost> <20140612232453.GR9508@dastard> <539B78F3.9070607@libero.it> <539BFF47.8060006@libero.it> <20140615221307.GE24386@tango.0pointer.de> In-Reply-To: <20140615221307.GE24386@tango.0pointer.de> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi Lennart, On 06/16/2014 12:13 AM, Lennart Poettering wrote: > I am not really following though why this trips up btrfs though. I am > not sure I understand why this breaks btrfs COW behaviour. I mean, > fallocate() isn't necessarily supposed to write anything really, it's > mostly about allocating disk space in advance. I would claim that > journald's usage of it is very much within the entire reason why it > exists... I performed several tests, trying different setups [1]. One of these was replacing the posix_fallocate() with a truncate, to check where is the problem. The conclusion was that *posix_fallocate() is NOT the problem*. In another reply you stated that systemd-journald appends some data at the end of file, then update some data in the middle. I think this is the reason because the file becomes quickly fragmented. [1] Let me to revise the english, the I will post the results. -- gpg @keyserver.linux.it: Goffredo Baroncelli (kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5