diff options
| author | Shrikanth Hegde <sshegde@linux.ibm.com> | 2026-09-28 11:07:19 +0530 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-09-28 08:44:41 +0200 |
| commit | 518b32bd5bb373aa334e4b73d359689071d50b5c (patch) | |
| tree | 6193da8ab7550b37c954e1fd5a8d91b6edd63f31 /include/linux | |
| parent | 06a49ef784acf91cee78d50c5307d400f86ccafb (diff) | |
cpumask: Introduce cpu_preferred_mask
Provide the preferred CPU infrastructure. Define get/set macros
which could be used to get/set CPU state as preferred.
CONFIG_PREFERRED_CPU will be selected by the driver which handles
steal time values. It is going to set/clear preferred CPU state.
This driver will be called steal_governor and it is introduced in
subsequent patches. It periodically computes the steal ratio and
decides on preferred CPU state.
A CPU is set to preferred when it becomes active. Later it may be
marked as non-preferred depending on steal ratio by the steal_governor.
Always maintain design construct of preferred is subset of active.
i.e. preferred ⊆ active ⊆ online ⊆ present ⊆ possible
With CONFIG_PREFERRED_CPU=n, ensure set_cpu_preferred is a nop and get
method returns the active state in that case.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260928053728.797539-5-sshegde@linux.ibm.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/cpumask.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 7c8f16797f94..bf89bb3f30f6 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -121,12 +121,20 @@ extern struct cpumask __cpu_enabled_mask; extern struct cpumask __cpu_present_mask; extern struct cpumask __cpu_active_mask; extern struct cpumask __cpu_dying_mask; + +#ifdef CONFIG_PREFERRED_CPU +extern struct cpumask __cpu_preferred_mask; +#else +#define __cpu_preferred_mask __cpu_active_mask +#endif + #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask) #define cpu_online_mask ((const struct cpumask *)&__cpu_online_mask) #define cpu_enabled_mask ((const struct cpumask *)&__cpu_enabled_mask) #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) #define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) +#define cpu_preferred_mask ((const struct cpumask *)&__cpu_preferred_mask) extern atomic_t __num_online_cpus; extern unsigned int __num_possible_cpus; @@ -1181,6 +1189,12 @@ void init_cpu_possible(const struct cpumask *src); #define set_cpu_active(cpu, active) assign_cpu((cpu), &__cpu_active_mask, (active)) #define set_cpu_dying(cpu, dying) assign_cpu((cpu), &__cpu_dying_mask, (dying)) +#ifdef CONFIG_PREFERRED_CPU +#define set_cpu_preferred(cpu, preferred) assign_cpu((cpu), &__cpu_preferred_mask, (preferred)) +#else +#define set_cpu_preferred(cpu, preferred) do { } while (0) +#endif + void set_cpu_online(unsigned int cpu, bool online); void set_cpu_possible(unsigned int cpu, bool possible); @@ -1275,6 +1289,11 @@ static __always_inline bool cpu_dying(unsigned int cpu) return cpumask_test_cpu(cpu, cpu_dying_mask); } +static __always_inline bool cpu_preferred(unsigned int cpu) +{ + return cpumask_test_cpu(cpu, cpu_preferred_mask); +} + #else #define num_online_cpus() 1U @@ -1313,6 +1332,11 @@ static __always_inline bool cpu_dying(unsigned int cpu) return false; } +static __always_inline bool cpu_preferred(unsigned int cpu) +{ + return cpu == 0; +} + #endif /* NR_CPUS > 1 */ #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu)) |