Re: [PATCH] PPC64 collect and export low-level cpu usage statistics

[Andrew Morton <akpm@osdl.org>]

Paul Mackerras <paulus@samba.org> wrote:
>
> POWER5 machines have a per-hardware-thread register which counts at a
> rate which is proportional to the percentage of cycles on which the
> cpu dispatches an instruction for this thread (if the thread gets all
> the dispatch cycles it counts at the same rate as the timebase
> register).  This register is also context-switched by the hypervisor.
> Thus it gives a fine-grained measure of the actual cpu usage by the
> thread over time.
> 
> This patch adds code to read this register every timer interrupt and
> on every context switch.

fyi: This patch consumes another entry from thread_struct.pad[]. 
ppc64-implement-a-vdso-and-use-it-for-signal-trampoline.patch consumes two
more entries, so with both patches, you have none left.