On Thu, Jul 12, 2012 at 4:35 PM, Asias He <asias@xxxxxxxxxx> wrote: > This patchset adds vhost-blk support. vhost-blk is a in kernel virito-blk > device accelerator. Compared to userspace virtio-blk implementation, vhost-blk > gives about 5% to 15% performance improvement. Why is it 5-15% faster? vhost-blk and the userspace virtio-blk you benchmarked should be doing basically the same thing: 1. An eventfd file descriptor is signalled when the vring has new requests available from the guest. 2. A thread wakes up and processes the virtqueue. 3. Linux AIO is used to issue host I/O. 4. An interrupt is injected into the guest. Does the vhost-blk implementation do anything fundamentally different from userspace? Where is the overhead that userspace virtio-blk has? I'm asking because it would be beneficial to fix the overhead (especially it that could speed up all userspace applications) instead of adding a special-purpose kernel module to work around the overhead. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
