Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH 2/2] cpuidle / menu: Return error code if there are no suitable states | Date | Wed, 30 Apr 2014 01:16:45 +0200 |
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On Tuesday, April 29, 2014 01:28:03 AM Rafael J. Wysocki wrote: > On Monday, April 28, 2014 01:14:32 PM Daniel Lezcano wrote: > > On 04/27/2014 02:55 PM, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > > > If there is a PM QoS latency limit and all of the sufficiently shallow > > > C-states are disabled, the cpuidle menu governor returns 0 which on > > > some systems is CPUIDLE_DRIVER_STATE_START and shouldn't be returned > > > if that C-state has been disabled. > > > > > > Fix the issue by modifying the menu governor to return an error code > > > in such situations. > > > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > --- > > > drivers/cpuidle/governors/menu.c | 2 +- > > > include/linux/cpuidle.h | 2 ++ > > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > > > Index: linux-pm/drivers/cpuidle/governors/menu.c > > > =================================================================== > > > --- linux-pm.orig/drivers/cpuidle/governors/menu.c > > > +++ linux-pm/drivers/cpuidle/governors/menu.c > > > @@ -296,7 +296,7 @@ static int menu_select(struct cpuidle_dr > > > data->needs_update = 0; > > > } > > > > > > - data->last_state_idx = 0; > > > + data->last_state_idx = CPUIDLE_DRIVER_STATE_POLL; > > > > > > /* Special case when user has set very strict latency requirement */ > > > if (unlikely(latency_req == 0)) > > > Index: linux-pm/include/linux/cpuidle.h > > > =================================================================== > > > --- linux-pm.orig/include/linux/cpuidle.h > > > +++ linux-pm/include/linux/cpuidle.h > > > @@ -217,8 +217,10 @@ static inline int cpuidle_register_gover > > > > > > #ifdef CONFIG_ARCH_HAS_CPU_RELAX > > > #define CPUIDLE_DRIVER_STATE_START 1 > > > +#define CPUIDLE_DRIVER_STATE_POLL 0 > > > #else > > > #define CPUIDLE_DRIVER_STATE_START 0 > > > +#define CPUIDLE_DRIVER_STATE_POLL (-ENXIO) > > > #endif > > > > > > #endif /* _LINUX_CPUIDLE_H */ > > > > Hi Rafael, > > > > CPUIDLE_DRIVER_STATE_START is only for x86. It introduces some confusion > > in the code. > > I won't disagree with that. > > > As only two drivers are concerned by it, wouldn't make > > sense to add the poll state to those driver directly instead of having > > the code hacked around ? (eg. insert the poll state in the common > > cpuidle code). > > Well, what about initializing data->last_state_idx to > (CPUIDLE_DRIVER_STATE_START - 1) in menu_select() instead of introducing the > new symbol for the time being and getting rid of CPUIDLE_DRIVER_STATE_START > separately?
Updated patch is appended for completness.
Thanks!
--- From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Subject: cpuidle / menu: Return (-1) if there are no suitable states
If there is a PM QoS latency limit and all of the sufficiently shallow C-states are disabled, the cpuidle menu governor returns 0 which on some systems is CPUIDLE_DRIVER_STATE_START and shouldn't be returned if that C-state has been disabled.
Fix the issue by modifying the menu governor to return (-1) in such situations.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> --- drivers/cpuidle/governors/menu.c | 2 +- include/linux/cpuidle.h | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-)
Index: linux-pm/drivers/cpuidle/governors/menu.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governors/menu.c +++ linux-pm/drivers/cpuidle/governors/menu.c @@ -296,7 +296,7 @@ static int menu_select(struct cpuidle_dr data->needs_update = 0; } - data->last_state_idx = 0; + data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1; /* Special case when user has set very strict latency requirement */ if (unlikely(latency_req == 0))
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