3 files changed, 63 insertions, 1 deletions

diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 41367c5c3c68..ff43e9268449 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -137,7 +137,7 @@ extern void synchronize_irq(unsigned int irq);
 
 struct task_struct;
 
-#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 static inline void account_system_vtime(struct task_struct *tsk)
 {
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index aca0ce675939..2cca9a92f5e5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1826,6 +1826,19 @@ extern void sched_clock_idle_sleep_event(void);
 extern void sched_clock_idle_wakeup_event(u64 delta_ns);
 #endif
 
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+/*
+ * An i/f to runtime opt-in for irq time accounting based off of sched_clock.
+ * The reason for this explicit opt-in is not to have perf penalty with
+ * slow sched_clocks.
+ */
+extern void enable_sched_clock_irqtime(void);
+extern void disable_sched_clock_irqtime(void);
+#else
+static inline void enable_sched_clock_irqtime(void) {}
+static inline void disable_sched_clock_irqtime(void) {}
+#endif
+
 extern unsigned long long
 task_sched_runtime(struct task_struct *task);
 extern unsigned long long thread_group_sched_runtime(struct task_struct *task);
diff --git a/kernel/sched.c b/kernel/sched.c
index 089be8adb074..9b302e355791 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1908,6 +1908,55 @@ static void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
         dec_nr_running(rq);
 }
 
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+
+static DEFINE_PER_CPU(u64, cpu_hardirq_time);
+static DEFINE_PER_CPU(u64, cpu_softirq_time);
+
+static DEFINE_PER_CPU(u64, irq_start_time);
+static int sched_clock_irqtime;
+
+void enable_sched_clock_irqtime(void)
+{
+        sched_clock_irqtime = 1;
+}
+
+void disable_sched_clock_irqtime(void)
+{
+        sched_clock_irqtime = 0;
+}
+
+void account_system_vtime(struct task_struct *curr)
+{
+        unsigned long flags;
+        int cpu;
+        u64 now, delta;
+
+        if (!sched_clock_irqtime)
+                return;
+
+        local_irq_save(flags);
+
+        now = sched_clock();
+        cpu = smp_processor_id();
+        delta = now - per_cpu(irq_start_time, cpu);
+        per_cpu(irq_start_time, cpu) = now;
+        /*
+         * We do not account for softirq time from ksoftirqd here.
+         * We want to continue accounting softirq time to ksoftirqd thread
+         * in that case, so as not to confuse scheduler with a special task
+         * that do not consume any time, but still wants to run.
+         */
+        if (hardirq_count())
+                per_cpu(cpu_hardirq_time, cpu) += delta;
+        else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD))
+                per_cpu(cpu_softirq_time, cpu) += delta;
+
+        local_irq_restore(flags);
+}
+
+#endif
+
 #include "sched_idletask.c"
 #include "sched_fair.c"
 #include "sched_rt.c"