On Tuesday, March 22, 2016 06:30:05 PM Peter Zijlstra wrote:

On Tue, Mar 22, 2016 at 01:19:39PM -0400, Chris Metcalf wrote:

quoted

When doing an nmi backtrace of many cores, most of which are idle,
the output is a little overwhelming and very uninformative.  Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".

We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the
interrupted PC to see if it lies within that section.

This commit suitably tags x86, arm64, and tile idle routines,
and only adds in the minimal framework for other architectures.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Chris Metcalf <redacted>

For some reason I found a few CPUs using poll_idle().

Rafael, when and why would that ever get selected as a useful idle
state? When the predicted idle time is so short even C1 isn't worth it?

Yes, that's the case.