From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: Re: less cores more iops / speed Date: Thu, 08 Nov 2012 16:14:32 +0100 Message-ID: <509BCC58.3070003@profihost.ag> References: <509ADA6A.9000807@profihost.ag> <509AF625.8040207@inktank.com> <509B03EA.9050701@inktank.com> <509B711D.3070206@profihost.ag> <509BB156.5080404@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.profihost.ag ([85.158.179.208]:51858 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751930Ab2KHPOl (ORCPT ); Thu, 8 Nov 2012 10:14:41 -0500 In-Reply-To: <509BB156.5080404@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson Cc: Joao Eduardo Luis , "ceph-devel@vger.kernel.org" Am 08.11.2012 14:19, schrieb Mark Nelson: > On 11/08/2012 02:45 AM, Stefan Priebe - Profihost AG wrote: >> Am 08.11.2012 01:59, schrieb Mark Nelson: >>> There's also the context switching overhead. It'd be interesting to >>> know how much the writer processes were shifting around on cores. >> What do you mean by that? I'm talking about the KVM guest not about the >> ceph nodes. > > in this case, is fio bouncing around between cores? Thanks you're correct. If i bind fio to two cores on a 8 core VM it runs with 16.000 iops. So it is a problem of KVM which let's the processes jump between cores a lot. Greets, Stefan