Nux, there is no way to set it for NVME as it only has [none] option in /sys/block/nvme0n1/queue/scheduler
Setting any scheduler for VM volume doesn't improve a thing. пт, 17 мая 2019 г., 20:21 Nux! <n...@li.nux.ro>: > 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" <users@cloudstack.apache.org>, "dev" < > d...@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/> > >>>> >
