I'm afraid I can't give you any pointers...hopefully someone with ceph tuning expertise could comment. (You might try the ceph mailing list at ceph-users at ceph.com) Chris On 08/25/2017 01:30 AM, chagg at foxmail.com wrote: > I use this command to launch a VM. It disk io is also about 20M Bps，Why？ > > /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 > > Thanks！ > -------------------------------------------------------------------------------- > chagg at foxmail.com > > *From:* chagg at foxmail.com <mailto:chagg at foxmail.com> > *Date:* 2017-08-25 10:05 > *To:* Chris Friesen <mailto:chris.friesen at windriver.com>; openstack > <mailto:openstack at lists.openstack.org> > *Subject:* Re: Re: [Openstack] guest rbd block device speed limit > This is my ceph performance data: > > Total time run: 30.370630 > Total writes made: 849 > Write size: 4194304 > Bandwidth (MB/sec): 111.819 > Stddev Bandwidth: 21.6665 > Max bandwidth (MB/sec): 124 > Min bandwidth (MB/sec): 0 > Average IOPS: 27 > Average Latency(s): 0.572236 > Stddev Latency(s): 0.421846 > Max latency(s): 4.06547 > Min latency(s): 0.121321 > > Thanks! > -------------------------------------------------------------------------------- > chagg at foxmail.com > > *From:* Chris Friesen <mailto:chris.friesen at windriver.com> > *Date:* 2017-08-24 23:14 > *To:* openstack at lists.openstack.org <mailto:openstack at lists.openstack.org> > *Subject:* Re: [Openstack] guest rbd block device speed limit > On 08/24/2017 01:04 AM, chagg at foxmail.com wrote: > > Hello: > > I am using openstack + libvirt + qemu-kvm. The speed of copying > files > > between virtual machines exceeds 300M Byte per second but the speed > of dd command: > > "watch dd oflag=direct,nonblock if=/dev/zero of=/opt/iotest1 bs=4M > count=10" > > is around 20M byte per second. Every guest is the same, and there > is no io > > tuning in libvirt. What can I do to unleash the speed of disk io > speed inside > > the guest? > > Thanks! > It looks like you're using ceph for your root disk. What sort of > performance do > you get accessing the ceph volumes from the host? > Chris > _______________________________________________ > Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack > Post to : openstack at lists.openstack.org > Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack >