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 > <mailto: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 >> <mailto: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.
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