From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YKOp0-00088d-2d for qemu-devel@nongnu.org; Sun, 08 Feb 2015 05:10:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YKOov-0004OQ-4H for qemu-devel@nongnu.org; Sun, 08 Feb 2015 05:10:34 -0500 Received: from mail-we0-x236.google.com ([2a00:1450:400c:c03::236]:43696) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YKOou-0004OI-KX for qemu-devel@nongnu.org; Sun, 08 Feb 2015 05:10:28 -0500 Received: by mail-we0-f182.google.com with SMTP id l61so21410815wev.13 for ; Sun, 08 Feb 2015 02:10:28 -0800 (PST) Sender: Paolo Bonzini Message-ID: <54D73610.7080005@redhat.com> Date: Sun, 08 Feb 2015 11:10:24 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <54D032FB.404@huawei.com> <54D038EB.9020508@huawei.com> <54D08BB2.1070400@redhat.com> <54D5F660.7030801@huawei.com> In-Reply-To: <54D5F660.7030801@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [question] the patch which affect performance of virtio-scsi List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Wangting (Kathy)" , qemu-devel On 07/02/2015 12:26, Wangting (Kathy) wrote: > OK, Thank you very much for your detailed explanation. > > But I have another question about the big change from qemu-1.5.3 to qemu-1.6.0-rc0. > > When I use ramdisk for IO performance testing, the result is as follows. > > [fio-test] rw bs iodepth jobs bw iops > ------------------------------------------------------------------------------------ > qemu-1.5.3 read 4k 32 1 285MB/s 73208 > qemu-1.6.0-rc0 read 4k 32 1 253MB/s 64967 > > And virtio-blk is the same. > > I know there are so many differences between qemu-1.5 and qemu-1.6, but I am confused about > what new features impact the performance so much. Do you know it? No, sorry. Please try newer versions first and see if this was fixed. QEMU 1.6 is more than a year old. Paolo