On 15/12/2016 09:04, Stefan Hajnoczi wrote: >> Does this feature only work for VirtIO? Does it work for SCSI or IDE? > This only works for virtio-blk and virtio-scsi. The virtio-scsi > dataplane support is more recent and I don't remember if it is complete. > I've CCed Fam and Paolo who worked on virtio-scsi dataplane. > > Now that you have mentioned that you aren't using virtio devices, there > is another source of lock contention that you will encounter. I/O > request submission takes place in the vcpu thread when ioeventfd is not > used. Only virtio uses ioeventfd so your current QEMU configuration is > unable to let the vcpu continue execution during I/O request submission. > > If you care about performance then using virtio devices is probably the > best choice. Try comparing against virtio-scsi dataplane - you should > see a lot less jitter.
Yes, virtio-scsi dataplane is complete. Paolo
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