From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=39907 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P17MG-0004rl-Hj for qemu-devel@nongnu.org; Wed, 29 Sep 2010 20:51:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1P17Lo-0000Sg-F6 for qemu-devel@nongnu.org; Wed, 29 Sep 2010 20:50:22 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:59639) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1P17Lo-0000SD-A5 for qemu-devel@nongnu.org; Wed, 29 Sep 2010 20:50:20 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e38.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id o8U0gVW4016469 for ; Wed, 29 Sep 2010 18:42:31 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id o8U0oGdQ234442 for ; Wed, 29 Sep 2010 18:50:16 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o8U0oG9b024395 for ; Wed, 29 Sep 2010 18:50:16 -0600 Received: from [127.0.0.1] (IBM-2AECC81F76A.beaverton.ibm.com [9.47.22.70]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id o8U0oFE9024319 for ; Wed, 29 Sep 2010 18:50:16 -0600 Message-ID: <4CA3DEC7.5070609@linux.vnet.ibm.com> Date: Wed, 29 Sep 2010 17:50:15 -0700 From: "Venkateswararao Jujjuri (JV)" MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] QEMU throughput is down with SMP List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu-development List Code: Mainline QEMU (git://git.qemu.org/qemu.git) Machine: LS21 blade. Disk: Local disk through VirtIO. Did not select any cache option. Defaulting to writethrough. Command tested: 3 parallel instances of : dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 QEMU with smp=1 19.3 MB/s + 19.2 MB/s + 18.6 MB/s = 57.1 MB/s QEMU with smp=4 15.3 MB/s + 14.1 MB/s + 13.6 MB/s = 43.0 MB/s Is this expected? Thanks, JV === Details === smp = 1 time dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw1 bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw2 bs=4k count=100000 & [root@localhost ~]# 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 21.2747 s, 19.3 MB/s real 0m21.377s user 0m0.040s sys 0m1.655s 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 21.2799 s, 19.2 MB/s real 0m21.374s user 0m0.046s sys 0m1.660s 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 22.0735 s, 18.6 MB/s real 0m22.153s user 0m0.043s sys 0m1.642s smp = 4 [root@localhost ~]# time dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw1 bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw2 bs=4k count=100000 & [root@localhost ~]# 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 26.8055 s, 15.3 MB/s real 0m26.869s user 0m0.079s sys 0m3.333s 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 28.9583 s, 14.1 MB/s real 0m29.018s user 0m0.053s sys 0m4.313s 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 30.1739 s, 13.6 MB/s real 0m30.238s user 0m0.065s sys 0m4.124s