Kernel or user may have special requirement on cpu response time, like
if a interrupt is pinned to a cpu, we don't want the cpu goes too deep
sleep. This patch can prevent this thing happen by consider per cpu
resume_latency setting in cpu sleep state selection in menu governor.
The pm_qos_resume_latency ask device to give reponse in this time. That's
similar with cpu cstates' entry_latency + exit_latency. But since
most of cpu cstate either has no entry_latency or add it into exit_latency
So, we just can restrict this time requirement as states exit_latency.
The 0 value of pm_qos_resume_latency is for no limitation according ABI
definition. So set the value 1 could get the 0 latency if it's needed.
Signed-off-by: Alex Shi <alex....@linaro.org>
To: linux-kernel@vger.kernel.org
Cc: Daniel Lezcano <daniel.lezc...@linaro.org>
Cc: Rasmus Villemoes <li...@rasmusvillemoes.dk>
Cc: Alex Shi <alex....@linaro.org>
Cc: Arjan van de Ven <ar...@linux.intel.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wyso...@intel.com>
---
drivers/cpuidle/governors/menu.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index bb58e2a..e354880 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -12,6 +12,7 @@
#include <linux/kernel.h>
#include <linux/cpuidle.h>
+#include <linux/cpu.h>
#include <linux/pm_qos.h>
#include <linux/time.h>
#include <linux/ktime.h>
@@ -281,17 +282,23 @@ 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;
--
2.8.1.101.g72d917a
