On 09/27/2012 03:33 PM, Seiji Aguchi wrote:
> 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.
>
Quite.
These functions are being invoked from the IDT, which is an indirect
pointer structure. When not being traced, there is absolutely no reason
why it should go through a thunk with tracepoints.
-hpa
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
