[Qemu-devel] [virtio-net] why does the tx virtqueue have a timer?

[Vasile Catalin-B50542]

1. Why does virtio-net have a timer to handle tx virtqueue?
2. Why isn't the virtqueue kick enough? (I see that both are set to 
handle jobs from virtqueue.)
3. What is the difference between regular timers and bh (bottom halves)? 
Why would you choose one over another?