Il 07/02/2013 14:31, Michael S. Tsirkin ha scritto:

quoted

Single means *this piece* (for example a request header) is single.  It
could still end up in an indirect buffer because QEMU does not support
mixed direct/indirect buffers.

Yes but why is the optimization worth it?
It makes sense if all we want to do is add a single buffer
in one go, this would give us virtqueue_add_buf_single.

But if we are building up an s/g list anyway,
speeding up one of the entries a tiny bit
seems very unlikely to be measureable.
No?

There is some optimization potential even in unrolling the loop, but
yes, it looks like I misunderstood.  I'll add virtqueue_add_buf_single
instead.

Paolo