On Wed, Mar 20, 2019, 1:16 PM Darrell Budic <bu...@onholyground.com> wrote:
> Inline: > > On Mar 20, 2019, at 4:25 AM, Roy Golan <rgo...@redhat.com> wrote: > > On Mon, 18 Mar 2019 at 22:14, Darrell Budic <bu...@onholyground.com> > wrote: > >> I agree, been checking some of my more disk intensive VMs this morning, >> switching them to noop definitely improved responsiveness. All the virtio >> ones I’ve found were using deadline (with RHEL/Centos guests), but some of >> the virt-scsi were using deadline and some were noop, so I’m not sure of a >> definitive answer on that level yet. >> >> For the hosts, it depends on what your backend is running. With a >> separate storage server on my main cluster, it doesn’t matter what the >> hosts set for me. You mentioned you run hyper converged, so I’d say it >> depends on what your disks are. If you’re using SSDs, go none/noop as they >> don’t benefit from the queuing. If they are HDDs, I’d test cfq or deadline >> and see which gave better latency and throughput to your vms. I’d guess >> you’ll find deadline to offer better performance, but cfq to share better >> amongst multiple VMs. Unless you use ZFS underneath, then go noop and let >> ZFS take care of it. >> >> On Mar 18, 2019, at 2:05 PM, Strahil <hunter86...@yahoo.com> wrote: >> >> Hi Darrel, >> >> Still, based on my experience we shouldn't queue our I/O in the VM, just >> to do the same in the Host. >> >> I'm still considering if I should keep deadline in my hosts or to switch >> to 'cfq'. >> After all, I'm using Hyper-converged oVirt and this needs testing. >> What I/O scheduler are you using on the host? >> >> > Our internal scale team is testing now 'throughput-performance' tuned > profile and it gives > promising results, I suggest you try it as well. > We will go over the results of a comparison against the virtual-guest > profile > , if there will be evidence for improvements we will set it as the default > (if it won't degrade small,medium scale envs). > > > I don’t think that will make a difference in this case. Both virtual-host > and virtual-guest include the throughput-performance profile, just with > “better” virtual memory tunings for guest and hosts. None of those 3 modify > the disk queue schedulers, by default, at least not on my Centos 7.6 > systems. > > Re my testing, I have virtual-host on my hosts and virtual-guest on my > guests already. > Unfortunately, the ideal scheduler really depends on storage configuration. Gluster, ZFS, iSCSI, FC, and NFS don't align on a single "best" configuration (to say nothing of direct LUNs on guests), then there's workload considerations. The scale team is aiming for a balanced "default" policy rather than one which is best for a specific environment. That said, I'm optimistic that the results will let us give better recommendations if your workload/storage benefits from a different scheduler > > _______________________________________________ > Users mailing list -- users@ovirt.org > To unsubscribe send an email to users-le...@ovirt.org > Privacy Statement: https://www.ovirt.org/site/privacy-policy/ > oVirt Code of Conduct: > https://www.ovirt.org/community/about/community-guidelines/ > List Archives: > https://lists.ovirt.org/archives/list/users@ovirt.org/message/FH5LLYXSEJKXTVVOAZCSMV6AAU33CNCA/ >
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