(Linus, look away, I'll resubmit it for 2.5.0)

The Linux pipe implementation is extremely inefficient for long,
blocking data transfers with pipes (e.g. what gcc -pipe does):
* 2 memcopies: user space->kernel buffer->user space
* 2 context switches for each transfered page.

Last march David Miller proposed using kiobuf for these data transfers,
I've written a new patch for 2.4.

(David's original patch contained 2 bugs: it doesn't protect properly
against multiple writers and it causes a BUG() in pipe_read() when data
is stored in both the kiobuf and the normal buffer)


--
	Manfred