[PATCH 2.6.26] Update wait_state_cycles in the VPA.

[Tony Breeds]

The hypervisor can look at the value in wait_state_cycles for an estimate of
how busy dedicated processors are.  Currently as the kernel never touches this
field so we appear to be 100% busy.  Record the duration the kernel is in
powersave and pass that to the HV to provide a reasonable indication of
utilisation.

Signed-off-by: Tony Breeds <tony at bakeyournoodle.com>
---
 arch/powerpc/platforms/pseries/setup.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index fdb9b1c..90555a3 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -393,6 +393,7 @@ static void pseries_dedicated_idle_sleep(void)
 { 
 	unsigned int cpu = smp_processor_id();
 	unsigned long start_snooze;
+	unsigned long in_purr, out_purr;
 
 	/*
 	 * Indicate to the HV that we are idle. Now would be
@@ -400,6 +401,7 @@ static void pseries_dedicated_idle_sleep(void)
 	 */
 	get_lppaca()->idle = 1;
 	get_lppaca()->donate_dedicated_cpu = 1;
+	in_purr = mfspr(SPRN_PURR);
 
 	/*
 	 * We come in with interrupts disabled, and need_resched()
@@ -432,6 +434,8 @@ static void pseries_dedicated_idle_sleep(void)
 
 out:
 	HMT_medium();
+	out_purr = mfspr(SPRN_PURR);
+	get_lppaca()->wait_state_cycles += out_purr - in_purr;
 	get_lppaca()->donate_dedicated_cpu = 0;
 	get_lppaca()->idle = 0;
 }
-- 
1.5.4.3


Yours Tony

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