Hi,

Any comments on the following?

I'm finding with high interrupt rates for some USB devices the menu governo=
r guesses wrong enough that throughput drops.

With the below tweak tests with fixed data sizes which were taking 12s to c=
omplete drop back to 9s.  Also my standby idle doesn't change before and af=
ter activity with our with out the patch.

What it does is simply timestamp incoming irqs, then in the menu governor w=
ill use current & last irq time delta to refine its guess as to how long sl=
eep will happen.

Regards,
Richard W.

Signed-off-by: Richard Woodruff <r-woodruff2@ti.com>

diff -purN img/2.6_kernel/arch/arm/kernel/irq.c 2.6_kernel/arch/arm/kernel/=
irq.c
--- img/2.6_kernel/arch/arm/kernel/irq.c        2008-04-03 22:43:09.0000000=
00 -0500
+++ 2.6_kernel/arch/arm/kernel/irq.c    2008-07-14 15:09:48.000000000 -0500
@@ -122,6 +131,8 @@ asmlinkage void __exception asm_do_IRQ(u

        irq_enter();

+       kstat_irq_stamp();
+
        desc_handle_irq(irq, desc);

        /* AT91 specific workaround */
diff -purN img/2.6_kernel/drivers/cpuidle/governors/menu.c 2.6_kernel/drive=
rs/cpuidle/governors/menu.c
--- img/2.6_kernel/drivers/cpuidle/governors/menu.c     2008-07-04 15:31:23=
.000000000 -0500
+++ 2.6_kernel/drivers/cpuidle/governors/menu.c 2008-07-14 15:22:55.0000000=
00 -0500
@@ -7,6 +7,7 @@
  */

 #include <linux/kernel.h>
+#include <linux/kernel_stat.h>
 #include <linux/cpuidle.h>
 #include <linux/latency.h>
 #include <linux/time.h>
@@ -70,6 +71,7 @@ static void menu_reflect(struct cpuidle_
        unsigned int measured_us =3D
                cpuidle_get_last_residency(dev) + data->elapsed_us;
        struct cpuidle_state *target =3D &dev->states[last_idx];
+       const unsigned int cpu =3D smp_processor_id();

        /*
         * Ugh, this idle state doesn't support residency measurements, so =
we
@@ -92,6 +94,10 @@ static void menu_reflect(struct cpuidle_
                        data->elapsed_us =3D -1;
                data->predicted_us =3D max(measured_us, data->last_measured=
_us);
        }
+
+       /* Guess & factor in interrupt wake rate */
+       data->predicted_us =3D min((s64)data->predicted_us, ktime_to_us(
+               ktime_sub(kstat_cpu(cpu).irq_now, kstat_cpu(cpu).irq_last))=
);
 }

 /**
diff -purN img/2.6_kernel/include/linux/kernel_stat.h 2.6_kernel/include/li=
nux/kernel_stat.h
--- img/2.6_kernel/include/linux/kernel_stat.h  2008-04-03 21:51:50.0000000=
00 -0500
+++ 2.6_kernel/include/linux/kernel_stat.h      2008-07-14 13:11:09.0000000=
00 -0500
@@ -7,6 +7,7 @@
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
 #include <asm/cputime.h>
+#include <linux/hrtimer.h>

 /*
  * 'kernel_stat.h' contains the definitions needed for doing
@@ -29,6 +30,8 @@ struct cpu_usage_stat {
 struct kernel_stat {
        struct cpu_usage_stat   cpustat;
        unsigned int irqs[NR_IRQS];
+       ktime_t irq_now;
+       ktime_t irq_last;
 };

 DECLARE_PER_CPU(struct kernel_stat, kstat);
@@ -52,6 +55,16 @@ static inline int kstat_irqs(int irq)
        return sum;
 }

+/*
+ * Provide hook to try and understand interrupt rate on a processor
+ */
+static inline void kstat_irq_stamp(void)
+{
+       const unsigned int cpu =3D smp_processor_id();
+       kstat_cpu(cpu).irq_last =3D kstat_cpu(cpu).irq_now;
+       kstat_cpu(cpu).irq_now =3D ktime_get();
+}
+
 extern void account_user_time(struct task_struct *, cputime_t);
 extern void account_user_time_scaled(struct task_struct *, cputime_t);
 extern void account_system_time(struct task_struct *, int, cputime_t);