On Wednesday 27 October 2010 01:43:25 Thomas Renninger wrote:
> cpu_idle events (transition into sleep state and exiting) are
> both fired in pm_idle().
>
> Entering sleep state and exiting should always get fired inside
> pm_idle() already.
>
> This is a revert of commit c882e0feb937af4e5b991cbd1c
Robert: I expect you tested this on a machine with no cpuidle
driver registered?
I should have had a deeper look at this at once, done so now:
Current cpu_idle, power_start/end (same before my changes) behavior
on X86 is rather weird (without this patch):
if pm_idle is:
poll_idle -> should throw double end events
default_idle -> only throws power_start, your patch
fixed that, but in the generic cpu_idle
thread function which always gets executed
also if pm_idle != default_idle
So Robert fixed this case, but at the wrong place.
cpuidle_idle_call -> depends whether intel_idle or acpi_idle
driver registered:
intel_idle -> throws a cpu idle state event, still double end
events (one from cpuidle, one from
process_{32,64}.c, due to Robert's patch
acpi_idle -> whether a power_start event is thrown at all
depends on (cmp with acpi_idle_do_entry()):
cx->entry_method == ACPI_CSTATE_FFH
will end up in a power_start event via:
acpi_processor_ffh_cstate_enter(cx)
mwait_idle_with_hints()
but it will not in case of:
cx->entry_method == ACPI_CSTATE_HALT
or IO based switching (the else path there):
/* IO port based C-state */
Again without this(my) patch you get:
poll_idle -> double end events
default_idle -> all is fine (with your patch)
cpuidle_idle_call
intel_idle registered -> double end events
acpi_idle registered -> double end events
start events may not be thrown
at all.
perf timechart can handle double end events, this may be
the reason this was overseen.
Argh, I tried to come up with patches, but run out of
time. I will send something soon.
I also found a bug in my userspace stuff: I forgot to convert
u64 to u32..., sorry about that.
I try to resend everything tomorrow.
Thomas
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