What happens when you set deadline scheduler in both HV and guest? -- Sent from the Delta quadrant using Borg technology!
Nux! www.nux.ro ----- Original Message ----- > From: "Ivan Kudryavtsev" <kudryavtsev...@bw-sw.com> > To: "users" <us...@cloudstack.apache.org>, "dev" <dev@cloudstack.apache.org> > Sent: Friday, 17 May, 2019 14:16:31 > Subject: Re: Poor NVMe Performance with KVM > BTW, You may think that the improvement is achieved by caching, but I clear > the cache with > sync & echo 3 > /proc/sys/vm/drop_caches > > So, can't claim for sure, need other opinion, but looks like for NVMe, > writethrough must be used if you want high IO rate. At least with Intel > p4500. > > > пт, 17 мая 2019 г., 20:04 Ivan Kudryavtsev <kudryavtsev...@bw-sw.com>: > >> Well, just FYI, I changed cache_mode from NULL (none), to writethrough >> directly in DB and the performance boosted greatly. It may be an important >> feature for NVME drives. >> >> Currently, on 4.11, the user can set cache-mode for disk offerings, but >> cannot for service offerings, which are translated to cache=none >> corresponding disk offerings. >> >> The only way is to use SQL to change that for root disk disk offerings. >> CreateServiceOffering API doesn't support cache mode. It can be a serious >> limitation for NVME users, because by default they could meet poor >> read/write performance. >> >> пт, 17 мая 2019 г., 19:30 Ivan Kudryavtsev <kudryavtsev...@bw-sw.com>: >> >>> Darius, thanks for your participation, >>> >>> first, I used 4.14 kernel which is the default one for my cluster. Next, >>> switched to 4.15 with dist-upgrade. >>> >>> Do you have an idea how to turn on amount of queues for virtio-scsi with >>> Cloudstack? >>> >>> пт, 17 мая 2019 г., 19:26 Darius Kasparavičius <daz...@gmail.com>: >>> >>>> Hi, >>>> >>>> I can see a few issues with your xml file. You can try using "queues" >>>> inside your disk definitions. This should help a little, not sure by >>>> how much for your case, but for my specific it went up by almost the >>>> number of queues. Also try cache directsync or writethrough. You >>>> should switch kernel if bugs are still there with 4.15 kernel. >>>> >>>> On Fri, May 17, 2019 at 12:14 PM Ivan Kudryavtsev >>>> <kudryavtsev...@bw-sw.com> wrote: >>>> > >>>> > 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/> >>>>
