RE: [PATCH v4] trace,x86: add x86 irq vector tracepoints

[Seiji Aguchi]

Hi,

> ... except the cost can be reduced to zero *AND* be made into a more general mechanism by simply hooking the IDT.

Thank you for giving me the comment.
In my understanding,  we can introduce a more general mechanism by sandwiching an existing handler between tracepoints.
The pseudo code is like this:

@@ -17,7 +18,7 @@ static void default_threshold_interrupt(void)
 
 void (*mce_threshold_vector)(void) = default_threshold_interrupt;
 
-asmlinkage void smp_threshold_interrupt(void)
+static void do_smp_threshold_interrupt(void)
 {
 	irq_enter();
 	exit_idle();
@@ -27,3 +28,10 @@ asmlinkage void smp_threshold_interrupt(void)
 	/* Ack only at the end to avoid potential reentry */
 	ack_APIC_irq();
 }
+
+asmlinkage void smp_threshold_interrupt(void) {
+	trace_arch_irq_vector_entry(THRESHOLD_APIC_VECTOR);
+	do_smp_threshold_interrupt();
+	trace_arch_irq_vector_exit(THRESHOLD_APIC_VECTOR);
+}

If I misunderstand something, please let me know.

Seiji
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