cloudstack-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Nux! <...@li.nux.ro>
Subject Re: Poor NVMe Performance with KVM
Date Fri, 17 May 2019 12:17:43 GMT
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_ia@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/>

Mime
View raw message