From 65d920646a1c720c5ba95b7643ab1b46167d9e6a Mon Sep 17 00:00:00 2001
From: Michael Cree <mcree@orcon.net.nz>
Date: Mon, 9 Aug 2010 17:20:05 -0700
Subject: [PATCH] alpha: add performance monitor interrupt counter

The following patches implement hardware performance events for the Alpha
EV67 and later CPUs.  I have had this running on a Compaq XP1000 (EV67,
single CPU) for a few days now.  Pretty cool -- discovered that the glibc
exp2() library routine uses on average 985 cycles to execute 777 CPU
instructions whereas Compaq's CPML library version of exp2() uses on
average 32 cycles to execute 47 CPU instructions to achieve the same
thing!

This patch:

Add performance monitor interrupt counternd and export the count to user
space via /proc/interrupts.

Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jay Estabrook <jay.estabrook@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/alpha/include/asm/hw_irq.h | 1 +
 arch/alpha/kernel/irq.c         | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/alpha/include/asm/hw_irq.h b/arch/alpha/include/asm/hw_irq.h
index a37db0f95092..5050ac81cd90 100644
--- a/arch/alpha/include/asm/hw_irq.h
+++ b/arch/alpha/include/asm/hw_irq.h
@@ -3,6 +3,7 @@
 
 
 extern volatile unsigned long irq_err_count;
+DECLARE_PER_CPU(unsigned long, irq_pmi_count);
 
 #ifdef CONFIG_ALPHA_GENERIC
 #define ACTUAL_NR_IRQS	alpha_mv.nr_irqs
diff --git a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c
index 7f912ba3d9ad..fe912984d9b1 100644
--- a/arch/alpha/kernel/irq.c
+++ b/arch/alpha/kernel/irq.c
@@ -31,6 +31,7 @@
 #include <asm/uaccess.h>
 
 volatile unsigned long irq_err_count;
+DEFINE_PER_CPU(unsigned long, irq_pmi_count);
 
 void ack_bad_irq(unsigned int irq)
 {
@@ -63,9 +64,7 @@ int irq_select_affinity(unsigned int irq)
 int
 show_interrupts(struct seq_file *p, void *v)
 {
-#ifdef CONFIG_SMP
 	int j;
-#endif
 	int irq = *(loff_t *) v;
 	struct irqaction * action;
 	unsigned long flags;
@@ -112,6 +111,10 @@ show_interrupts(struct seq_file *p, void *v)
 			seq_printf(p, "%10lu ", cpu_data[j].ipi_count);
 		seq_putc(p, '\n');
 #endif
+		seq_puts(p, "PMI: ");
+		for_each_online_cpu(j)
+			seq_printf(p, "%10lu ", per_cpu(irq_pmi_count, j));
+		seq_puts(p, "          Performance Monitoring\n");
 		seq_printf(p, "ERR: %10lu\n", irq_err_count);
 	}
 	return 0;