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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: Alex Shi <alex.shi@linaro.org>
Acked-by: Rik van Riel <riel@redhat.com>
[ rjw : Subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Alex Shi 2017-01-12 21:27:04 +08:00 committed by Rafael J. Wysocki
parent 8e37e1a2a3
commit 9908859aca
1 changed files with 7 additions and 0 deletions
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7
drivers/cpuidle/governors/menu.c
View File

@ -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 @@ again:
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;