Designing a Userspace Disk I/O Scheduler for Modern Datastores (2016)

Re:Designing a Userspace Disk I/O Scheduler for Modern Datas... by wtallis on Thursday April 19, 2018 @02:21PM (#16878553)

I think what you're talking isn't actually SR-IOV; that involves having multiple virtual functions on a single PCIe device, but you're just talking about using the IOMMU to partition your devices into disjoint domains without trying to give multiple VMs access to the same peripheral.

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Re:Designing a Userspace Disk I/O Scheduler for Modern Datas... by derefr on Thursday April 19, 2018 @02:38PM (#16878756)

This used to be a real distinction (when computers had plain PCI peripherals), but it's not really any more.

SR-IOV is the name for the PCI SIG's standardization of the control protocol between the CPU and the IOMMU in respect to controlling PCIe devices. Even if you're just mapping a device to a single VM, if it's a PCIe device, you're using SR-IOV to do it. (The ability to do this might still be referred to as VT-d in Intel-platform BIOSes, but if you look in your OS device tree, the functionality enabled with an "Enable Intel VT-d" setting should appear as an SR-IOV controller. You could think of VT-d as the part in the CPU that speaks the SR-IOV protocol to the IOMMU.)

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