cloudstack-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ivan Kudryavtsev <kudryavtsev...@bw-sw.com>
Subject Re: Poor NVMe Performance with KVM
Date Fri, 17 May 2019 14:08:52 GMT
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! <nux@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_ia@bw-sw.com>
> > To: "users" <users@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_ia@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_ia@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 <daznis@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_ia@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/>
> >>>>
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message