[리눅스커널] 인터럽트 핸들러 실행 시각 측정 디버깅 패치

 
diff --git a/drivers/mailbox/bcm2835-mailbox.c b/drivers/mailbox/bcm2835-mailbox.c
index a03aeed..e353beb 100644
--- a/drivers/mailbox/bcm2835-mailbox.c
+++ b/drivers/mailbox/bcm2835-mailbox.c
@@ -72,17 +72,29 @@ static struct bcm2835_mbox *bcm2835_link_mbox(struct mbox_chan *link)
        return container_of(link->mbox, struct bcm2835_mbox, controller);
 }
 
+#define HANDLE_TIME 100
+
 static irqreturn_t bcm2835_mbox_irq(int irq, void *dev_id)
 {
+       u64 diff, start_time, curr_time;
        struct bcm2835_mbox *mbox = dev_id;
        struct device *dev = mbox->controller.dev;
        struct mbox_chan *link = &mbox->controller.chans[0];
 
+       start_time = sched_clock();
        while (!(readl(mbox->regs + MAIL0_STA) & ARM_MS_EMPTY)) {
                u32 msg = readl(mbox->regs + MAIL0_RD);
                dev_dbg(dev, "Reply 0x%08X\n", msg);
                mbox_chan_received_data(link, &msg);
        }
+
+       curr_time = sched_clock();
+       diff = curr_time - start_time;
+
+       if (diff > HANDLE_TIME)
+               trace_printk("interrupt: elapsed: %llu, start: %llu \n",
+                               diff, start_time);
+
        return IRQ_HANDLED;
 }