From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.thunk.org ([74.207.234.97]:54818 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951AbcBLQxX (ORCPT ); Fri, 12 Feb 2016 11:53:23 -0500 Date: Fri, 12 Feb 2016 11:53:19 -0500 From: Theodore Ts'o To: Premysl Kouril Cc: Andi Kleen , linux-fsdevel@vger.kernel.org Subject: Re: EXT4 vs LVM performance for VMs Message-ID: <20160212165319.GB7928@thunk.org> References: <87twlee9to.fsf@tassilo.jf.intel.com> <20160212133825.GJ11298@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Feb 12, 2016 at 03:13:26PM +0100, Premysl Kouril wrote: > The performance results which I posted in my original post are after > all the block allocation is done. In other words: on the testing > machine we do a first fio run which writes and allocates the testing > file (during this first run the fio performance is actually much worse > that what I reported, single VM performance is about 700 IOPS) and > then we do second fio run and we take the benchmark numbers from this > second run. So you allocated the file using a random write workload, so the file was probably not very contiguous. Whereas when you allocated the LVM volume, it was probably allocated contiguously. You can use the filefrag tool to see how fragmented the file might be. All of this being said, what are you trying to do? If you are happy using LVM, feel free to use it. If there are specific features that you want out of the file system, it's best that you explicitly identify what you want, and so we can minimize the cost of the features of what you want. Cheers, - Ted