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cpuidle/powerpc: Fix smt_snooze_delay functionality.

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smt_snooze_delay was designed to  delay idle loop's nap entry
in the native idle code before it got  ported over to use as part of
the cpuidle framework.

A -ve value  assigned to smt_snooze_delay should result in
busy looping, in other words disabling the entry to nap state.

	- https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html

This particular functionality can be achieved currently by
echo 1 > /sys/devices/system/cpu/cpu*/state1/disable
but it is broken when one assigns -ve value to  the smt_snooze_delay
variable either via sysfs entry or ppc64_cpu util.

This patch aims to fix this, by disabling nap state when smt_snooze_delay
variable is set to -ve value.

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Deepthi Dharwar
2012-10-03 18:42:18 +00:00
committed by Benjamin Herrenschmidt
parent 817deb05df
commit 8ea959a17f
3 changed files with 20 additions and 10 deletions
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4
arch/powerpc/include/asm/processor.h
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@@ -388,9 +388,9 @@ extern int powersave_nap; /* set if nap mode can be used in idle loop */
extern void power7_nap(void);
#ifdef CONFIG_PSERIES_IDLE
extern void update_smt_snooze_delay(int snooze);
extern void update_smt_snooze_delay(int cpu, int residency);
#else
static inline void update_smt_snooze_delay(int snooze) {}
static inline void update_smt_snooze_delay(int cpu, int residency) {}
#endif
extern void flush_instruction_cache(void);