Hi Konrad, On Fri, Jul 10, 2020 at 11:33:09AM -0400, Konrad Rzeszutek Wilk wrote: > .snip.. > > Just to recap the proposal, the idea is to add some restrictions to the > > operations (sqe, register, fixed file) to safely allow untrusted applications > > or guests to use io_uring queues. > > Hi! > > This is neat and quite cool - but one thing that keeps nagging me is > what how much overhead does this cut from the existing setup when you use > virtio (with guests obviously)? I need to do more tests, but the preliminary results that I reported on the original proposal [1] show an overhead of ~ 4.17 uS (with iodepth=1) when I'm using virtio ring processed in a dedicated iothread: - 73 kIOPS using virtio-blk + QEMU iothread + io_uring backend - 104 kIOPS using io_uring passthrough > That is from a high level view the > beaty of io_uring being passed in the guest is you don't have the > virtio ring -> io_uring processing, right? Right, and potentially we can share the io_uring queues directly to the guest userspace applications, cutting down the cost of Linux block layer in the guest. Thanks for your feedback, Stefano [1] https://lore.kernel.org/io-uring/20200609142406.upuwpfmgqjeji4lc@steredhat/
