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Commit 9908859a authored by Alex Shi's avatar Alex Shi Committed by Rafael J. Wysocki
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cpuidle/menu: add per CPU PM QoS resume latency consideration 



There may be special requirements on CPU response time, like if a
interrupt is pinned to a CPU, that CPU should not go into excessively
deep idle states.  For this reason, add a mechanism for adding
PM QoS resume latency constraints for individual CPUs and modify the
menu governor to take them into account.

To that end, extend the device PM QoS pm_qos_resume_latency attribute
to CPUs, which is possible, because the exit latency for CPUs is
effectively equivalent to the resume latency for devices.

Signed-off-by: default avatarAlex Shi <alex.shi@linaro.org>
Acked-by: default avatarRik van Riel <riel@redhat.com>
[ rjw : Subject & changelog ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 8e37e1a2

drivers/cpuidle/governors/menu.c

+7 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/tick.h>

#include <linux/sched.h>

#include <linux/math64.h>

#include <linux/cpu.h>



/*

 * Please note when changing the tuning values:
@@ -280,17 +281,23 @@ static unsigned int get_typical_interval(struct menu_device *data) 
static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)

{

	struct menu_device *data = this_cpu_ptr(&menu_devices);

	struct device *device = get_cpu_device(dev->cpu);

	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);

	int i;

	unsigned int interactivity_req;

	unsigned int expected_interval;

	unsigned long nr_iowaiters, cpu_load;

	int resume_latency = dev_pm_qos_read_value(device);



	if (data->needs_update) {

		menu_update(drv, dev);

		data->needs_update = 0;

	}



	/* 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))

		return 0;