On Mon, Mar 21, 2016 at 12:15:12PM -0400, Chris Metcalf wrote:

On 03/21/2016 11:42 AM, Peter Zijlstra wrote:

quoted

The most common idle function for x86 is: mwait_idle_with_hints(),
trouble is, its an inline, so I'm not sure adding __cpuidle to it does
anything.

No, you're right, it wouldn't help.  I didn't look at the drivers/cpuidle
subsystem at all in my patch, since I'm not that familiar with it,
but it seems like tagging acpi_processor_ffh_cstate_enter(), as the
only user of mwait_idle_with_hints(), will do the job.

intel_idle() also uses it.

quoted

I've yet to find the magic objdump incantation to check. Or rather
objdump -h doesn't appear to list .cpuidle.text at all :/

I'm probably doing something silly...

The easiest way to check for a given function is just to look
at the "nm -n" output and see that all the functions you expect
to reflect idle behavior are in the cpuidle begin/end range.

# nm -n ivb-ep-build/vmlinux | awk '/__cpuidle_text_start/ {p=1} {if (p) print $0} /__cpuidle_text_end/ {p=0}'
ffffffff81b16ca8 T __cpuidle_text_start
ffffffff81b16cb0 T default_idle
ffffffff81b16e50 t mwait_idle
ffffffff81b17080 t cpu_idle_poll
ffffffff81b17280 T default_idle_call
ffffffff81b172be T __cpuidle_text_end

So no intel_idle for me..

objdump -h certainly works to show .cpuidle.text if you look at
individual objects (e.g. arch/x86/kernel/process.o) but by the time
you're looking at the linked vmlinux image they have all been linked
into the giant .text section.

Indeed.