lkml.org 
[lkml]   [2013]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subjectacpi_pad mwait usage
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 *)&current_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)

\
 
 \ /
  Last update: 2013-11-19 10:21    [W:0.073 / U:0.572 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site