>-----Original Message----- >From: Mark Lord [mailto:lkml@xxxxxx] >Sent: Friday, January 04, 2008 1:53 PM >To: Pallipadi, Venkatesh >Cc: Arjan van de Ven; Andrew Morton; abelay@xxxxxxxxxx; >lenb@xxxxxxxxxx; Ingo Molnar; linux-kernel@xxxxxxxxxxxxxxx; >linux-acpi@xxxxxxxxxxxxxxx; rjw@xxxxxxx >Subject: Re: + restore-missing-sysfs-max_cstate-attr.patch >added to -mm tree > >Mark Lord wrote: >> Venki Pallipadi wrote: >>> Reintroduce run time configurable max_cstate for !CPU_IDLE case. >>> >>> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> >>> >>> Index: linux-2.6.24-rc/drivers/acpi/processor_idle.c >>> =================================================================== >>> --- linux-2.6.24-rc.orig/drivers/acpi/processor_idle.c >>> +++ linux-2.6.24-rc/drivers/acpi/processor_idle.c >>> @@ -76,7 +76,11 @@ static void (*pm_idle_save) (void) __rea >>> #define PM_TIMER_TICKS_TO_US(p) (((p) * >>> 1000)/(PM_TIMER_FREQUENCY/1000)) >>> >>> static unsigned int max_cstate __read_mostly = >ACPI_PROCESSOR_MAX_POWER; >>> +#ifdef CONFIG_CPU_IDLE >>> module_param(max_cstate, uint, 0000); >>> +#else >>> +module_param(max_cstate, uint, 0644); >>> +#endif >>> static unsigned int nocst __read_mostly; >>> module_param(nocst, uint, 0000); >>> >> .. >> >> I'll try and re-test with this on Friday. >.. > >Okay, with !CONFIG_CPU_IDLE, this works fine -- same as 2.6.23 >and earlier. > Good to know. Atleast we do not have a regression for 2.6.24 now. >> Meanwhile, can you give a short summary of how behaviour differs >> between CONFIG_CPU_IDLE and !CONFIG_CPU_IDLE ?? >> >> I'm not at all clear on how this really affects things. > With CPU_IDLE, the C-state policy is removed from acpi driver. Ideally policy should have nothing to do with ACPI, as ACPI only provides the C-state mechanisms. So, with CPU_IDLE, it is not easy to control this variable through a acpi driver module at run time. Also, the latency interface that was mentioned before is to serve the same purpose in a more clear manner (based on the wakeup latency) instead of a C-state number which may not mean much from the end user point of view. I will look at why latency does not work on a single core system soon(Was that with UP kernel or SMP kernel?). That way we will have a proper cover for this with CPU_IDLE in future. Thanks, Venki - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
