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 <[email protected]> To: [email protected] Cc: [email protected] Cc: Ulf Hansson <[email protected]> Cc: Daniel Lezcano <[email protected]> Cc: Rasmus Villemoes <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Rik van Riel <[email protected]> Cc: "Rafael J. Wysocki" <[email protected]> --- 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 07e36bb..8d6d25c 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -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; -- 2.8.1.101.g72d917a
