| Message ID | 20171027020124.GA10233@intel.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On Fri, Oct 27, 2017 at 4:01 AM, Ramesh Thomas <ramesh.thomas@intel.com> wrote: > Individual CPUs may have special requirements to not enter > deep idle states. For example, a CPU running real time > applications would not want to enter deep idle states to > avoid latency impacts. At the same time other CPUs that > do not have such a requirement could allow deep idle > states to save power. > > This was already implemented in the menu governor. > Implementing similar changes in the ladder governor which > gets selected when CONFIG_NO_HZ and CONFIG_NO_HZ_IDLE are not > set. Refer following commits for the menu governor changes. > > commit 9908859acaa9 ("cpuidle/menu: add per CPU PM QoS resume > latency consideration") > commit 6dbf5cea05a7 ("cpuidle: menu: Avoid taking spinlock for > accessing QoS values") > > Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com> > --- > > v2: > - use PM_QOS_RESUME_LATENCY_NO_CONSTRAINT for "no constraint" value > Should be applied over https://patchwork.kernel.org/patch/10024157/ > > drivers/cpuidle/governors/ladder.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c > index ce1a2ff..1ad8745 100644 > --- a/drivers/cpuidle/governors/ladder.c > +++ b/drivers/cpuidle/governors/ladder.c > @@ -17,6 +17,7 @@ > #include <linux/pm_qos.h> > #include <linux/jiffies.h> > #include <linux/tick.h> > +#include <linux/cpu.h> > > #include <asm/io.h> > #include <linux/uaccess.h> > @@ -67,10 +68,16 @@ static int ladder_select_state(struct cpuidle_driver *drv, > struct cpuidle_device *dev) > { > struct ladder_device *ldev = this_cpu_ptr(&ladder_devices); > + struct device *device = get_cpu_device(dev->cpu); > struct ladder_device_state *last_state; > int last_residency, last_idx = ldev->last_state_idx; > int first_idx = drv->states[0].flags & CPUIDLE_FLAG_POLLING ? 1 : 0; > int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); > + int resume_latency = dev_pm_qos_raw_read_value(device); > + > + if (resume_latency < latency_req && > + resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT) > + latency_req = resume_latency; > > /* Special case when user has set very strict latency requirement */ > if (unlikely(latency_req == 0)) { > -- > 2.7.4 > Looks good to me. I'll queue it up if nobody objects. Thanks, Rafael
On 2017-10-27 at 09:59:38 +0200, Rafael J. Wysocki wrote: > On Fri, Oct 27, 2017 at 4:01 AM, Ramesh Thomas <ramesh.thomas@intel.com> wrote: > > Individual CPUs may have special requirements to not enter > > deep idle states. For example, a CPU running real time > > applications would not want to enter deep idle states to > > avoid latency impacts. At the same time other CPUs that > > do not have such a requirement could allow deep idle > > states to save power. > > > > This was already implemented in the menu governor. > > Implementing similar changes in the ladder governor which > > gets selected when CONFIG_NO_HZ and CONFIG_NO_HZ_IDLE are not > > set. Refer following commits for the menu governor changes. > > > > commit 9908859acaa9 ("cpuidle/menu: add per CPU PM QoS resume > > latency consideration") > > commit 6dbf5cea05a7 ("cpuidle: menu: Avoid taking spinlock for > > accessing QoS values") > > > > Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com> > > --- > > > > v2: > > - use PM_QOS_RESUME_LATENCY_NO_CONSTRAINT for "no constraint" value > > Should be applied over https://patchwork.kernel.org/patch/10024157/ > > > > drivers/cpuidle/governors/ladder.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c > > index ce1a2ff..1ad8745 100644 > > --- a/drivers/cpuidle/governors/ladder.c > > +++ b/drivers/cpuidle/governors/ladder.c > > @@ -17,6 +17,7 @@ > > #include <linux/pm_qos.h> > > #include <linux/jiffies.h> > > #include <linux/tick.h> > > +#include <linux/cpu.h> > > > > #include <asm/io.h> > > #include <linux/uaccess.h> > > @@ -67,10 +68,16 @@ static int ladder_select_state(struct cpuidle_driver *drv, > > struct cpuidle_device *dev) > > { > > struct ladder_device *ldev = this_cpu_ptr(&ladder_devices); > > + struct device *device = get_cpu_device(dev->cpu); > > struct ladder_device_state *last_state; > > int last_residency, last_idx = ldev->last_state_idx; > > int first_idx = drv->states[0].flags & CPUIDLE_FLAG_POLLING ? 1 : 0; > > int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); > > + int resume_latency = dev_pm_qos_raw_read_value(device); > > + > > + if (resume_latency < latency_req && > > + resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT) > > + latency_req = resume_latency; > > > > /* Special case when user has set very strict latency requirement */ > > if (unlikely(latency_req == 0)) { > > -- > > 2.7.4 > > > > Looks good to me. > > I'll queue it up if nobody objects. > Hi Rafael, This patch would apply as is over your new PM QoS changes. If you need me to repost please let me know. Thanks, Ramesh
diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c index ce1a2ff..1ad8745 100644 --- a/drivers/cpuidle/governors/ladder.c +++ b/drivers/cpuidle/governors/ladder.c @@ -17,6 +17,7 @@ #include <linux/pm_qos.h> #include <linux/jiffies.h> #include <linux/tick.h> +#include <linux/cpu.h> #include <asm/io.h> #include <linux/uaccess.h> @@ -67,10 +68,16 @@ static int ladder_select_state(struct cpuidle_driver *drv, struct cpuidle_device *dev) { struct ladder_device *ldev = this_cpu_ptr(&ladder_devices); + struct device *device = get_cpu_device(dev->cpu); struct ladder_device_state *last_state; int last_residency, last_idx = ldev->last_state_idx; int first_idx = drv->states[0].flags & CPUIDLE_FLAG_POLLING ? 1 : 0; int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); + int resume_latency = dev_pm_qos_raw_read_value(device); + + if (resume_latency < latency_req && + resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT) + latency_req = resume_latency; /* Special case when user has set very strict latency requirement */ if (unlikely(latency_req == 0)) {
Individual CPUs may have special requirements to not enter deep idle states. For example, a CPU running real time applications would not want to enter deep idle states to avoid latency impacts. At the same time other CPUs that do not have such a requirement could allow deep idle states to save power. This was already implemented in the menu governor. Implementing similar changes in the ladder governor which gets selected when CONFIG_NO_HZ and CONFIG_NO_HZ_IDLE are not set. Refer following commits for the menu governor changes. commit 9908859acaa9 ("cpuidle/menu: add per CPU PM QoS resume latency consideration") commit 6dbf5cea05a7 ("cpuidle: menu: Avoid taking spinlock for accessing QoS values") Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com> --- v2: - use PM_QOS_RESUME_LATENCY_NO_CONSTRAINT for "no constraint" value Should be applied over https://patchwork.kernel.org/patch/10024157/ drivers/cpuidle/governors/ladder.c | 7 +++++++ 1 file changed, 7 insertions(+)