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<div><span></span>I use this command to launch a VM. It disk io is also about 20M Bps，Why？</div><div><br></div>
<div><span style="color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">/usr/libexec/qemu-kvm -m 1024 -drive format=rbd,file=rbd:volumes/d9bda7d7-f68a-45ea-84a1-f50faa44b801_disk,cache=writeback -vnc :10 -usb -usbdevice tablet</span></div><div><span style="color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);"><br></span></div><div><span style="color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Thanks！</span></div><hr style="width: 210px; height: 1px;" color="#b5c4df" size="1" align="left">
<div><span><div style="MARGIN: 10px; FONT-FAMILY: verdana; FONT-SIZE: 10pt"><div>chagg@foxmail.com</div></div></span></div>
<blockquote style="margin-top: 0px; margin-bottom: 0px; margin-left: 0.5em;"><div> </div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><div style="PADDING-RIGHT: 8px; PADDING-LEFT: 8px; FONT-SIZE: 12px;FONT-FAMILY:tahoma;COLOR:#000000; BACKGROUND: #efefef; PADDING-BOTTOM: 8px; PADDING-TOP: 8px"><div><b>From:</b> <a href="mailto:chagg@foxmail.com">chagg@foxmail.com</a></div><div><b>Date:</b> 2017-08-25 10:05</div><div><b>To:</b> <a href="mailto:chris.friesen@windriver.com">Chris Friesen</a>; <a href="mailto:openstack@lists.openstack.org">openstack</a></div><div><b>Subject:</b> Re: Re: [Openstack] guest rbd block device speed limit</div></div></div><div><div class="FoxDiv20170825152847048388">
<div><span></span><div>This is my ceph performance data:</div><div><br></div><div> Total time run: 30.370630<br>Total writes made: 849<br>Write size: 4194304<br>Bandwidth (MB/sec): 111.819<br>Stddev Bandwidth: 21.6665<br>Max bandwidth (MB/sec): 124<br>Min bandwidth (MB/sec): 0<br>Average IOPS: 27<br>Average Latency(s): 0.572236<br>Stddev Latency(s): 0.421846<br>Max latency(s): 4.06547<br>Min latency(s): 0.121321<br></div></div><div><br></div>
<div>Thanks!</div><hr style="width: 210px; height: 1px;" color="#b5c4df" size="1" align="left">
<div><span><div style="MARGIN: 10px; FONT-FAMILY: verdana; FONT-SIZE: 10pt"><div>chagg@foxmail.com</div></div></span></div>
<blockquote style="margin-top: 0px; margin-bottom: 0px; margin-left: 0.5em;"><div> </div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><div style="PADDING-RIGHT: 8px; PADDING-LEFT: 8px; FONT-SIZE: 12px;FONT-FAMILY:tahoma;COLOR:#000000; BACKGROUND: #efefef; PADDING-BOTTOM: 8px; PADDING-TOP: 8px"><div><b>From:</b> <a href="mailto:chris.friesen@windriver.com">Chris Friesen</a></div><div><b>Date:</b> 2017-08-24 23:14</div><div><b>To:</b> <a href="mailto:openstack@lists.openstack.org">openstack@lists.openstack.org</a></div><div><b>Subject:</b> Re: [Openstack] guest rbd block device speed limit</div></div></div><div><div>On 08/24/2017 01:04 AM, chagg@foxmail.com wrote:</div>
<div>> Hello:</div>
<div>> I am using openstack + libvirt + qemu-kvm. The speed of copying files</div>
<div>> between virtual machines exceeds 300M Byte per second but the speed of dd command:</div>
<div>> "watch dd oflag=direct,nonblock if=/dev/zero of=/opt/iotest1 bs=4M count=10"</div>
<div>> is around 20M byte per second. Every guest is the same, and there is no io</div>
<div>> tuning in libvirt. What can I do to unleash the speed of disk io speed inside</div>
<div>> the guest?</div>
<div>> Thanks!</div>
<div> </div>
<div>It looks like you're using ceph for your root disk. What sort of performance do </div>
<div>you get accessing the ceph volumes from the host?</div>
<div> </div>
<div>Chris</div>
<div> </div>
<div> </div>
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