Hi, Is there any concern on this patch?
Regards Alex On 08/25/2016 04:42 PM, Alex Shi wrote: > 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: Alex Shi <[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 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; >
