On 10/05/2016 11:40, Kevin Wolf wrote: > > Regarding performance, I'm thinking about a guest with 8 disks (queue > > depth 32). The worst case is when the guest submits 32 requests at once > > but the Linux AIO event limit has already been reached. Then the disk > > is starved until other disks' requests complete. > > Sounds like a valid concern.
Oh, so you're concerned about the non-dataplane case. My suspicion is that, with such a number of outstanding I/O, you probably have bad performance unless you use dataplane. Also, aio=threads has had a 64 I/O limit for years and we've never heard about problems with stuck I/O. But I agree that it's one area to keep an eye on. Paolo
