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I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all processes(VMs) get fair slices of storage time? If so, how can one VM I/O interfere with another's VM I/O when CFQ is being used?

Environment is CentOS6.5+OpenStack+KVM+Ceph

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  • And which operating system? I'd probably be using the deadline scheduler instead of CFQ regardless, though.
    – ewwhite
    Sep 8, 2014 at 12:59
  • OS is Linux, can CFQ be found elsewhere?
    – BlackBeret
    Sep 8, 2014 at 13:01
  • How "use deadline" answers "how does using CFQ affects the "Nosy Neighbor" problem"?
    – BlackBeret
    Sep 8, 2014 at 13:02
  • Because the standard practice for configuring KVM atop modern Linux is to use the Deadline scheduler. By "which OS", I meant "which distribution/kernel/release", because the schedulers have evolved over time.
    – ewwhite
    Sep 8, 2014 at 13:04
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    Distribution is CentOS 6.5. See here, I/O scheduler selection doesn't make much difference for Ceph: ceph.com/community/…
    – BlackBeret
    Sep 8, 2014 at 13:07

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