cpuidle: ladder: Add per CPU PM QoS resume latency support
PATCH 1/1 cpuidle: ladder: Add per CPU PM QoS resume latency support
Individual CPUs may have special requirements to not enter deep idle states. For example, a CPU running real time applications would not want to enter deep idle states to avoid latency impacts. At the same time other CPUs that do not have such a requirement could allow deep idle states to save power.
This was already implemented in the menu governor. Implementing similar changes in the ladder governor which gets selected when CONFIG_NO_HZ and CONFIG_NO_HZ_IDLE are not set. Refer following commits for the menu governor changes.
commit 9908859acaa9 ("cpuidle/menu: add per CPU PM QoS resume latency consideration")
commit 6dbf5cea05a7 ("cpuidle: menu: Avoid taking spinlock for accessing QoS values")
--- drivers/cpuidle/governors/ladder.c | 7 +++++++ 1 file changed, 7 insertions(+)
drivers/cpuidle/governors/ladder.c +7 -0
@@ -17,6 +17,7 @@#include <linux/pm_qos.h> #include <linux/jiffies.h> #include <linux/tick.h> +#include <linux/cpu.h> #include <asm/io.h> #include <linux/uaccess.h>
@@ -67,10 +68,16 @@ static int ladder_select_state(struct cpuidle_driver *drv, struct cpuidle_device *dev) {struct ladder_device *ldev =this_cpu_ptr (&ladder_devices); +struct device *device =get_cpu_device (dev->cpu);struct ladder_device_state *last_state;int last_residency, last_idx = ldev->last_state_idx;int first_idx = drv->states[0 ].flags &CPUIDLE_FLAG_POLLING ?1 :0 ;int latency_req =pm_qos_request (PM_QOS_CPU_DMA_LATENCY ); +int resume_latency =dev_pm_qos_raw_read_value (device); + +/* resume_latency is 0 means no restriction */ +if (resume_latency && resume_latency < latency_req) + latency_req = resume_latency;/* Special case when user has set very strict latency requirement */ if (unlikely (latency_req ==0 )) {
Signature · 1 line
2.7.4