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authorThara Gopinath <thara.gopinath@linaro.org>2020-02-22 03:52:07 +0300
committerIngo Molnar <mingo@kernel.org>2020-03-06 14:57:18 +0300
commitad58cc5cc50ca8423cf630778594bd38252a0a58 (patch)
treeac5a8bd30da9b9c4df835f56b913be081d61e18b /include/linux/arch_topology.h
parent36a0df85d2e85e1929e8cd607e19243e5a2754e7 (diff)
downloadlinux-ad58cc5cc50ca8423cf630778594bd38252a0a58.tar.xz
drivers/base/arch_topology: Add infrastructure to store and update instantaneous thermal pressure
Add architecture specific APIs to update and track thermal pressure on a per CPU basis. A per CPU variable thermal_pressure is introduced to keep track of instantaneous per CPU thermal pressure. Thermal pressure is the delta between maximum capacity and capped capacity due to a thermal event. topology_get_thermal_pressure can be hooked into the scheduler specified arch_scale_thermal_pressure to retrieve instantaneous thermal pressure of a CPU. arch_set_thermal_pressure can be used to update the thermal pressure. Considering topology_get_thermal_pressure reads thermal_pressure and arch_set_thermal_pressure writes into thermal_pressure, one can argue for some sort of locking mechanism to avoid a stale value. But considering topology_get_thermal_pressure can be called from a system critical path like scheduler tick function, a locking mechanism is not ideal. This means that it is possible the thermal_pressure value used to calculate average thermal pressure for a CPU can be stale for up to 1 tick period. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200222005213.3873-4-thara.gopinath@linaro.org
Diffstat (limited to 'include/linux/arch_topology.h')
-rw-r--r--include/linux/arch_topology.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 3015ecbb90b1..88a115e81f27 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -33,6 +33,16 @@ unsigned long topology_get_freq_scale(int cpu)
return per_cpu(freq_scale, cpu);
}
+DECLARE_PER_CPU(unsigned long, thermal_pressure);
+
+static inline unsigned long topology_get_thermal_pressure(int cpu)
+{
+ return per_cpu(thermal_pressure, cpu);
+}
+
+void arch_set_thermal_pressure(struct cpumask *cpus,
+ unsigned long th_pressure);
+
struct cpu_topology {
int thread_id;
int core_id;