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Date: Sun, 5 Oct 2014 18:24:58 -0500 (CDT)
From: Christoph Lameter <cl@...ux.com>
To: Thomas Gleixner <tglx@...utronix.de>
cc: Richard Cochran <richardcochran@...il.com>,
linux-kernel@...r.kernel.org
Subject: Re: Why do we still have 32 bit counters? Interrupt counters overflow
within 50 days
Subject: Increase irq counters to 64 bit V2
V1->V2
- Wrong sie and percpu alloc.
- Use u64 so that this will also work on 32 bit machines
Irq counters can overflow easily if they are just 32 bit.
For example the timer interrupt occurs 1000 times per second, so
it is predictable that the timer interrupt will overflow in
2^ 32 / 1000 [interrupts per second] / 86400 [seconds in a day]
which results in 46 days.
Other irq counters for devices may wrap even faster for example
those for high speed networking devices.
This patch is needed to avoid the counter overflow by increasing
the counters to 64 bit.
Signed-off-by: Christoph Lameter <cl@...ux.com>
Index: linux/arch/x86/include/asm/processor.h
===================================================================
--- linux.orig/arch/x86/include/asm/processor.h
+++ linux/arch/x86/include/asm/processor.h
@@ -432,7 +432,7 @@ DECLARE_PER_CPU_FIRST(union irq_stack_un
DECLARE_INIT_PER_CPU(irq_stack_union);
DECLARE_PER_CPU(char *, irq_stack_ptr);
-DECLARE_PER_CPU(unsigned int, irq_count);
+DECLARE_PER_CPU(u64, irq_count);
extern asmlinkage void ignore_sysret(void);
#else /* X86_64 */
#ifdef CONFIG_CC_STACKPROTECTOR
Index: linux/arch/x86/kernel/cpu/common.c
===================================================================
--- linux.orig/arch/x86/kernel/cpu/common.c
+++ linux/arch/x86/kernel/cpu/common.c
@@ -1144,7 +1144,7 @@ EXPORT_PER_CPU_SYMBOL(current_task);
DEFINE_PER_CPU(char *, irq_stack_ptr) =
init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64;
-DEFINE_PER_CPU(unsigned int, irq_count) __visible = -1;
+DEFINE_PER_CPU(u64, irq_count) __visible = -1;
DEFINE_PER_CPU(int, __preempt_count) = INIT_PREEMPT_COUNT;
EXPORT_PER_CPU_SYMBOL(__preempt_count);
Index: linux/include/linux/irqdesc.h
===================================================================
--- linux.orig/include/linux/irqdesc.h
+++ linux/include/linux/irqdesc.h
@@ -41,7 +41,7 @@ struct irq_desc;
*/
struct irq_desc {
struct irq_data irq_data;
- unsigned int __percpu *kstat_irqs;
+ u64 __percpu *kstat_irqs;
irq_flow_handler_t handle_irq;
#ifdef CONFIG_IRQ_PREFLOW_FASTEOI
irq_preflow_handler_t preflow_handler;
@@ -51,7 +51,7 @@ struct irq_desc {
unsigned int core_internal_state__do_not_mess_with_it;
unsigned int depth; /* nested irq disables */
unsigned int wake_depth; /* nested wake enables */
- unsigned int irq_count; /* For detecting broken IRQs */
+ u64 irq_count; /* For detecting broken IRQs */
unsigned long last_unhandled; /* Aging timer for unhandled count */
unsigned int irqs_unhandled;
atomic_t threads_handled;
Index: linux/include/linux/kernel_stat.h
===================================================================
--- linux.orig/include/linux/kernel_stat.h
+++ linux/include/linux/kernel_stat.h
@@ -51,7 +51,7 @@ DECLARE_PER_CPU(struct kernel_cpustat, k
extern unsigned long long nr_context_switches(void);
-extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
+extern u64 kstat_irqs_cpu(unsigned int irq, int cpu);
extern void kstat_incr_irq_this_cpu(unsigned int irq);
static inline void kstat_incr_softirqs_this_cpu(unsigned int irq)
Index: linux/kernel/irq/debug.h
===================================================================
--- linux.orig/kernel/irq/debug.h
+++ linux/kernel/irq/debug.h
@@ -11,7 +11,7 @@
static inline void print_irq_desc(unsigned int irq, struct irq_desc *desc)
{
- printk("irq %d, desc: %p, depth: %d, count: %d, unhandled: %d\n",
+ printk("irq %d, desc: %p, depth: %d, count: %llu, unhandled: %d\n",
irq, desc, desc->depth, desc->irq_count, desc->irqs_unhandled);
printk("->handle_irq(): %p, ", desc->handle_irq);
print_symbol("%s\n", (unsigned long)desc->handle_irq);
Index: linux/kernel/irq/irqdesc.c
===================================================================
--- linux.orig/kernel/irq/irqdesc.c
+++ linux/kernel/irq/irqdesc.c
@@ -140,7 +140,7 @@ static struct irq_desc *alloc_desc(int i
if (!desc)
return NULL;
/* allocate based on nr_cpu_ids */
- desc->kstat_irqs = alloc_percpu(unsigned int);
+ desc->kstat_irqs = alloc_percpu(u64);
if (!desc->kstat_irqs)
goto err_desc;
@@ -532,7 +532,7 @@ void kstat_incr_irq_this_cpu(unsigned in
kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
}
-unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
+u64 kstat_irqs_cpu(unsigned int irq, int cpu)
{
struct irq_desc *desc = irq_to_desc(irq);
Index: linux/kernel/irq/proc.c
===================================================================
--- linux.orig/kernel/irq/proc.c
+++ linux/kernel/irq/proc.c
@@ -248,7 +248,7 @@ static int irq_spurious_proc_show(struct
{
struct irq_desc *desc = irq_to_desc((long) m->private);
- seq_printf(m, "count %u\n" "unhandled %u\n" "last_unhandled %u ms\n",
+ seq_printf(m, "count %llu\n" "unhandled %u\n" "last_unhandled %u ms\n",
desc->irq_count, desc->irqs_unhandled,
jiffies_to_msecs(desc->last_unhandled));
return 0;
@@ -450,7 +450,7 @@ int show_interrupts(struct seq_file *p,
seq_printf(p, "%*d: ", prec, i);
for_each_online_cpu(j)
- seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
+ seq_printf(p, "%10llu ", kstat_irqs_cpu(i, j));
if (desc->irq_data.chip) {
if (desc->irq_data.chip->irq_print_chip)
--
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