Ingo Molnar writes:

Note, i left out this bit from the commit - we need to find a better 
solution than to allow ugly warnings on PowerPC.

Could we use the kernel's u64 type directly perhaps? That would 
allow us to change all __u64 to u64 in all of tools/perf/ which is a 
nice clean-up in any case.

This is userspace, we can use "u64" however we like. :)  I'll cook up
a patch to add "typedef unsigned long long u64" and change __u64 to
u64.

Paul.