From owner-freebsd-fs@FreeBSD.ORG Thu Apr 11 17:02:57 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id AEE99FB8 for ; Thu, 11 Apr 2013 17:02:57 +0000 (UTC) (envelope-from break19@gmail.com) Received: from mail-qa0-f50.google.com (mail-qa0-f50.google.com [209.85.216.50]) by mx1.freebsd.org (Postfix) with ESMTP id 7675AA7D for ; Thu, 11 Apr 2013 17:02:57 +0000 (UTC) Received: by mail-qa0-f50.google.com with SMTP id bv4so400267qab.2 for ; Thu, 11 Apr 2013 10:02:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=DQ1iT9Qd4XzdRJLl2E1Jpg2BPFlxxV849t28cjZxhcE=; b=xR7JqPZiC4c7Yfqr9jCNCA7b5cFatWHGGfgiqENA1OKpBELrPF+BVzlhvcm4+ZCnpS ypm2b3LKkM4qUwN8tahoXZAIHQb1EhILkWBraS/sdB3dtzyhxVlZy/iIAItXCMl62xHd ZgOA/eggjMY0jCUlVXmc/5K3SOf7fMK0hpdo3zuvk5031AKTKQWrKJ4fYYImw3Kc0mhY 1GiQkiYKD//FNX7Lq5kAzPa4l2Zrcq/4SHX7smYSpymzXq4OZkgG81wnr5Akv4oFADQ0 zSqyi++QnnPO1xvOAmk2YxtYhwBA0MPyjg7lh7gD8L6B5CCHPUWldFVL+elN1w9EanEn xoLQ== X-Received: by 10.229.120.82 with SMTP id c18mr1901163qcr.10.1365699776758; Thu, 11 Apr 2013 10:02:56 -0700 (PDT) Received: from [192.168.0.198] (231.sub-70-196-129.myvzw.com. [70.196.129.231]) by mx.google.com with ESMTPS id ds5sm8400995qab.11.2013.04.11.10.02.54 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 11 Apr 2013 10:02:55 -0700 (PDT) Message-ID: <5166ECBA.1090005@gmail.com> Date: Thu, 11 Apr 2013 12:02:50 -0500 From: Chuck Burns User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 To: freebsd-fs@freebsd.org Subject: Re: ZFS slow reads for unallocated blocks References: <5166EA43.7050700@platinum.linux.pl> In-Reply-To: <5166EA43.7050700@platinum.linux.pl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Apr 2013 17:02:57 -0000 On 4/11/2013 11:52 AM, Adam Nowacki wrote: > This one is quite weird - reads from files that were created and resized > with ftruncate (so no actual data on disk) are considerably slower and > use more CPU time than files with data. If compression is enabled this > will also affect files with long runs of zeroes as ZFS won't write any > data to disk in this case. There is no I/O on the pool during the read > tests - all fits into 10GB ARC. > > FreeBSD storage 9.1-RELEASE FreeBSD 9.1-RELEASE #0: Sat Feb 23 15:51:26 > UTC 2013 root@storage:/usr/obj/usr/src/sys/GENERIC amd64 Sounds like it could be a CPU bottleneck? How about some cpu info? -- Chuck Burns