Linux questions

["Jan Beulich" <jbeulich@novell.com>]

1) Is there a particular reason Jeremy's sched_clock() variant isn't being
used in linux-2.6.18-hg? Specifically, are there any known downsides to
that approach?

2) What is the reason for the inconsistent use of rmb() vs. barrier() in
time-xen.c? It would seem to me that rmb() should be sufficient in all
cases.

3) Why is it that x86-64's __smp_call_function_single(), just like native,
uses cpu_relax() in its wait-for-response loops, while __smp_call_function()
as well as i386's smp_call_function() use barrier(), other than native?

Thanks, Jan