Messages in this thread | | | Date | Fri, 10 Jul 2020 18:20:17 +0200 | From | Stefano Garzarella <> | Subject | Re: [PATCH RFC 0/3] io_uring: add restrictions to support untrusted applications and guests |
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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/
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