From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39145) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5rnn-00080M-2Y for qemu-devel@nongnu.org; Fri, 19 Jun 2015 04:37:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z5rni-0008C4-QQ for qemu-devel@nongnu.org; Fri, 19 Jun 2015 04:37:31 -0400 Received: from mail-wi0-x234.google.com ([2a00:1450:400c:c05::234]:38702) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5rni-0008Bt-IG for qemu-devel@nongnu.org; Fri, 19 Jun 2015 04:37:26 -0400 Received: by wibdq8 with SMTP id dq8so11676037wib.1 for ; Fri, 19 Jun 2015 01:37:26 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <5583D4C3.5060409@redhat.com> Date: Fri, 19 Jun 2015 10:37:23 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <7c4c87b8.111fa.14df75bb798.Coremail.cauchy-love@163.com> <20150616130539.GC29405@stefanha-thinkpad.redhat.com> <79b03cb4.2428.14e0957997f.Coremail.cauchy-love@163.com> In-Reply-To: <79b03cb4.2428.14e0957997f.Coremail.cauchy-love@163.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: cauchy-love , Stefan Hajnoczi Cc: qemu-devel@nongnu.org On 19/06/2015 03:03, cauchy-love wrote: > I have tried your qemu cammand line but got no luck (the embedded os > have no virtio support but this is not the problem i think). The > problem probably lies in the host kernel version as it is the only > difference for my tests. I traced the guest kernel and found the ATA > drivers always used non-DMA mode (CentOS 7 and CentOS 6.5 are the > same at this point). You can use perf to see what's the difference. Perhaps CentOS 6.5 used ext4 and 7 uses XFS? Though in general XFS is the faster one... Paolo