Re: Perform mmap and poll on PUD character devices

[Roger Pau Monné <roger.pau%entel.upc.edu@localhost>]

> I can't see how a userland implementation can have better performances
> than an all in-kernel implementation. There are more context switches,
> which are notr so cheap with Xen.

From what I understand using blktap with Xen provides better
performance because it is designed specifically for this task (attach
disks to virtual machines), and uses asynchronous I/O, not because
it's implemented in userspace (if the whole thing was implemented
inside the kernel it will of course be faster, but it would also be
more dangerous regarding the security of the Dom0).