Messages in this thread Patch in this message | | | Date | Wed, 4 Oct 2017 21:46:18 -0700 | From | Ramesh Thomas <> | Subject | [PATCH] cpuidle: ladder: Add per CPU PM QoS resume latency support |
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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")
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com> --- drivers/cpuidle/governors/ladder.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c index ce1a2ff..f7cfee7 100644 --- a/drivers/cpuidle/governors/ladder.c +++ b/drivers/cpuidle/governors/ladder.c @@ -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)) { -- 2.7.4
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