linux-kernel - Re: Tracing of power:power

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Date:	Wed, 05 May 2010 10:31:21 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ronny Tschüter <Ronny.Tschueter@...dresden.de>
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Tracing of power:power_start events doesn't work

On Wed, 2010-05-05 at 16:11 +0200, Ronny Tschüter wrote:

>   /*
>    * Include the apic definitions for x86 to have the APIC timer related 
> defines
> @@ -796,6 +797,18 @@ static int acpi_idle_bm_check(void)
>    */
>   static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
>   {
> +    switch (cx->type) {
> +    case ACPI_STATE_C1:
> +        trace_power_start(POWER_CSTATE, 1);
> +        break;
> +    case ACPI_STATE_C2:
> +        trace_power_start(POWER_CSTATE, 2);
> +        break;
> +    case ACPI_STATE_C3:
> +        trace_power_start(POWER_CSTATE, 3);
> +        break;
> +    }
> +

Depending on gcc, the above can bloat the code since each call to
trace_power_start() is a macro expanded. Try to call it just once.
Perhaps one of the following:


	trace_power_start(POWER_CSTATE,
		cx->type == ACPI_STATE_C1 ? 1 :
		cx->type == ACPI_STATE_C2 ? 2 :
		3);

Or make a local variable instead, although the above would compile out
completely if tracing is not enabled.


	int type:

	switch (cx->type) {
	case ACPI_STATE_C1:
		type = 1;
		break;
	case ACPI_STATE_C2:
		type = 2;
		break;
	case ACPI_STATE_C3:
		type = 3;
		break;
	}
	trace_power_start(POWER_CSTATE, type);

-- Steve

>       /* Don't trace irqs off for idle */
>       stop_critical_timings();
>       if (cx->entry_method == ACPI_CSTATE_FFH) {
> 


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