From: Renaud Mariana Subject: Re: HUGE slowdown when doing dpkg with ext4 over nbd Date: Wed, 7 Dec 2016 10:52:48 +0100 (CET) Message-ID: <1339224178.8897979.1481104368542.JavaMail.zimbra@online.net> References: <1621417488.8583313.1481030030711.JavaMail.zimbra@online.net> <78AEFE7B-685B-4B4E-A15E-E3F6D99DD343@dilger.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Andreas Dilger Return-path: Received: from mail.online.net ([62.210.16.11]:55191 "EHLO mail.online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751512AbcLGJxW (ORCPT ); Wed, 7 Dec 2016 04:53:22 -0500 In-Reply-To: <78AEFE7B-685B-4B4E-A15E-E3F6D99DD343@dilger.ca> Sender: linux-ext4-owner@vger.kernel.org List-ID: Here are my answers, hope it will help solve this issue, thanks. Recap: dpkg kibana on ext4 over a nbd device takes 10 minutes with xfs it's only 30s. with ext4 no extends only 30s. kernels : 4.5.7 has this issue as older kernel like 4.4.34 The issue is also when nbd client & server run on same host How small are the files? here is the histogram of file sizes : http://pasteboard.co/6HC3nKyk2.png We can see 5000 files around 512 Bytes. dpkg using fallocate() ? Yes, there are 16044 calls by the same process what are these uninitialized extents ? Cheers, Renaud