Messages in this thread Patch in this message | | | Date | Tue, 19 Nov 2013 10:00:19 +0100 | From | Peter Zijlstra <> | Subject | acpi_pad mwait usage |
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Hi Len, Rafeal,
I stumbled over acpi_pad (yuck! ;-), but noticed that you don't set the task in polling mode while using mwait. This means we'll still happily send an IPI to wake you up.
A little something like the below should do; you might even be able to remove the smp_mb() but since it is completely undocumented (another fail) I couldn't tell if the implied barrier in current_set_polling_and_test() suffices to replace it, so I left it.
If it compiles and works; change it to a proper SOB:
Maybe-Signed-off-by: Peter Zijlstra <peterz@infradead.org> --- drivers/acpi/acpi_pad.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c index fc6008fbce35..e9126efe7786 100644 --- a/drivers/acpi/acpi_pad.c +++ b/drivers/acpi/acpi_pad.c @@ -195,8 +195,10 @@ static int power_saving_thread(void *data) __monitor((void *)¤t_thread_info()->flags, 0, 0); smp_mb(); - if (!need_resched()) + if (!current_set_polling_and_test()) { __mwait(power_saving_mwait_eax, 1); + __current_clr_polling(); + } start_critical_timings(); if (lapic_marked_unstable)
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