Re: [patch 2/3] ACPI: Keep TSC stable, when lapic_timer_c2_ok is set

Andrew Morton
2007-05-07T06:45:26Z

On Mon, 30 Apr 2007 10:43:33 -0000 Thomas Gleixner <tglx@linutronix.de> wrote:

> The local apic timer stop in C2 resp. C3 states is coupled with the
> stop of the TSC. When the local apic timer is marked stable in C2
> on the kernel commandline, then keep the TSC marked stable in C2 as well.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> ---
> drivers/acpi/processor_idle.c | 19 ++++++++-----------
> 1 file changed, 8 insertions(+), 11 deletions(-)
>
> Index: linux-2.6/drivers/acpi/processor_idle.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/processor_idle.c
> +++ linux-2.6/drivers/acpi/processor_idle.c
> @@ -305,18 +305,23 @@ static void acpi_state_timer_broadcast(s
> struct acpi_processor_cx *cx,
> int broadcast)
> {
> -#ifdef CONFIG_GENERIC_CLOCKEVENTS
> -
> int state = cx - pr->power.states;
>
> if (state >= pr->power.timer_broadcast_on_state) {
> +
> +#ifdef CONFIG_GENERIC_CLOCKEVENTS
> unsigned long reason;
>
> reason = broadcast ? CLOCK_EVT_NOTIFY_BROADCAST_ENTER :
> CLOCK_EVT_NOTIFY_BROADCAST_EXIT;
> clockevents_notify(reason, &pr->id);
> - }
> #endif
> +
> +#ifdef CONFIG_GENERIC_TIME
> + /* TSC halts in C2/3, so notify users */
> + mark_tsc_unstable();
> +#endif
> + }
> }
>
> #else
> @@ -481,10 +486,6 @@ static void acpi_processor_idle(void)
> /* Get end time (ticks) */
> t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
>
> -#ifdef CONFIG_GENERIC_TIME
> - /* TSC halts in C2, so notify users */
> - mark_tsc_unstable();
> -#endif
> /* Re-enable interrupts */
> local_irq_enable();
> current_thread_info()->status |= TS_POLLING;
> @@ -523,10 +524,6 @@ static void acpi_processor_idle(void)
> acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
> }
>
> -#ifdef CONFIG_GENERIC_TIME
> - /* TSC halts in C3, so notify users */
> - mark_tsc_unstable();
> -#endif
> /* Re-enable interrupts */
> local_irq_enable();
> current_thread_info()->status |= TS_POLLING;
>
> --

I'm now up to the third or fourth time where I need to try to repair this
patch against churn in Len's tree. I'm not sure what I'm doing and that
changelog is of little help to me.

I think I'll drop it. Please work it with Len.