Nux, I use Ubuntu 16.04 with "none" scheduler and the latest kernel 4.15. Guest is Ubuntu 18.04 with Noop scheduler for scsi-virtio and "none" for virtio.
Thanks. пт, 17 мая 2019 г., 19:18 Nux! <n...@li.nux.ro>: > Hi, > > What HV is that? CentOS? Are you using the right tuned profile? What about > in the guest? Which IO scheduler? > > -- > Sent from the Delta quadrant using Borg technology! > > Nux! > www.nux.ro > > ----- Original Message ----- > > From: "Ivan Kudryavtsev" <kudryavtsev...@bw-sw.com> > > To: "users" <users@cloudstack.apache.org> > > Sent: Friday, 17 May, 2019 10:13:50 > > Subject: Poor NVMe Performance with KVM > > > Hello, colleagues. > > > > Hope, someone could help me. I just deployed a new VM host with Intel > P4500 > > local storage NVMe drive. > > > > From Hypervisor host I can get expected performance, 200K RIOPS, 3GBs > with > > FIO, write performance is also high as expected. > > > > I've created a new KVM VM Service offering with virtio-scsi controller > > (tried virtio as well) and VM is deployed. Now I try to benchmark it with > > FIO. Results are very strange: > > > > 1. Read/Write with large blocks (1M) shows expected performance (my > limits > > are R=1000/W=500 MBs). > > > > 2. Write with direct=0 leads to expected 50K IOPS, while write with > > direct=1 leads to very moderate 2-3K IOPS. > > > > 3. Read with direct=0, direct=1 both lead to 3000 IOPS. > > > > During the benchmark I see VM IOWAIT=20%, while host IOWAIT is 0% which > is > > strange. > > > > So, basically, from inside VM my NVMe works very slow when small IOPS are > > executed. From the host, it works great. > > > > I tried to mount the volume with NBD to /dev/nbd0 and benchmark. Read > > performance is nice. Maybe someone managed to use NVME with KVM with > small > > IOPS? > > > > The filesystem is XFS, previously tried with EXT4 - results are the same. > > > > This is the part of VM XML definition generated by CloudStack: > > > > <devices> > > <emulator>/usr/bin/kvm-spice</emulator> > > <disk type='file' device='disk'> > > <driver name='qemu' type='qcow2' cache='none' discard='unmap'/> > > <source > > file='/var/lib/libvirt/images/6809dbd0-4a15-4014-9322-fe9010695934'/> > > <backingStore type='file' index='1'> > > <format type='raw'/> > > <source > > file='/var/lib/libvirt/images/ac43742c-3991-4be1-bff1-7617bf4fc6ef'/> > > <backingStore/> > > </backingStore> > > <target dev='sda' bus='scsi'/> > > <iotune> > > <read_bytes_sec>1048576000</read_bytes_sec> > > <write_bytes_sec>524288000</write_bytes_sec> > > <read_iops_sec>100000</read_iops_sec> > > <write_iops_sec>50000</write_iops_sec> > > </iotune> > > <serial>6809dbd04a1540149322</serial> > > <alias name='scsi0-0-0-0'/> > > <address type='drive' controller='0' bus='0' target='0' unit='0'/> > > </disk> > > <disk type='file' device='cdrom'> > > <driver name='qemu' type='raw'/> > > <backingStore/> > > <target dev='hdc' bus='ide'/> > > <readonly/> > > <alias name='ide0-1-0'/> > > <address type='drive' controller='0' bus='1' target='0' unit='0'/> > > </disk> > > <controller type='scsi' index='0' model='virtio-scsi'> > > <alias name='scsi0'/> > > <address type='pci' domain='0x0000' bus='0x00' slot='0x09' > > function='0x0'/> > > </controller> > > > > So, what I see now, is that it works slower than couple of two Samsung > 960 > > PRO which is extremely strange. > > > > Thanks in advance. > > > > > > -- > > With best regards, Ivan Kudryavtsev > > Bitworks LLC > > Cell RU: +7-923-414-1515 > > Cell USA: +1-201-257-1512 > > WWW: http://bitworks.software/ <http://bw-sw.com/> >
