| Message ID | 1444921326-22574-1-git-send-email-ulf.hansson@linaro.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On Thu, Oct 15 2015 at 09:02 -0600, Ulf Hansson wrote: >Measure latency does by itself contribute to an increased latency, thus we >should avoid it when it isn't needed. > >Genpd measures latencies in the system PM phase for the ->start|stop() >callbacks and is thus affecting the system PM suspend/resume time. >Moreover these latencies are validated only at runtime PM suspend/resume. > >To this reasoning, let's decide to leave these measurements out of the >system PM phase. There should be plenty of occasions during runtime PM to >perform these measurements anyway. > >Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Lina Iyer <lina.iyer@linaro.org> Thanks, Lina >--- > drivers/base/power/domain.c | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > >diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c >index 6e1bcde..a1c3ec4 100644 >--- a/drivers/base/power/domain.c >+++ b/drivers/base/power/domain.c >@@ -90,8 +90,12 @@ static struct generic_pm_domain *dev_to_genpd(struct device *dev) > return pd_to_genpd(dev->pm_domain); > } > >-static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev) >+static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev, >+ bool timed) > { >+ if (!timed) >+ return GENPD_DEV_CALLBACK(genpd, int, stop, dev); >+ > return GENPD_DEV_TIMED_CALLBACK(genpd, int, stop, dev, > stop_latency_ns, "stop"); > } >@@ -434,7 +438,7 @@ static int pm_genpd_runtime_suspend(struct device *dev) > if (ret) > return ret; > >- ret = genpd_stop_dev(genpd, dev); >+ ret = genpd_stop_dev(genpd, dev, true); > if (ret) { > genpd_restore_dev(genpd, dev, true); > return ret; >@@ -779,7 +783,7 @@ static int pm_genpd_suspend_noirq(struct device *dev) > || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))) > return 0; > >- genpd_stop_dev(genpd, dev); >+ genpd_stop_dev(genpd, dev, false); > > /* > * Since all of the "noirq" callbacks are executed sequentially, it is >@@ -820,7 +824,7 @@ static int pm_genpd_resume_noirq(struct device *dev) > pm_genpd_sync_poweron(genpd, true); > genpd->suspended_count--; > >- return genpd_start_dev(genpd, dev, true); >+ return genpd_start_dev(genpd, dev, false); > } > > /** >@@ -928,7 +932,7 @@ static int pm_genpd_freeze_noirq(struct device *dev) > if (IS_ERR(genpd)) > return -EINVAL; > >- return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev); >+ return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev, false); > } > > /** >@@ -948,7 +952,8 @@ static int pm_genpd_thaw_noirq(struct device *dev) > if (IS_ERR(genpd)) > return -EINVAL; > >- return genpd->suspend_power_off ? 0 : genpd_start_dev(genpd, dev, true); >+ return genpd->suspend_power_off ? >+ 0 : genpd_start_dev(genpd, dev, false); > } > > /** >@@ -1042,7 +1047,7 @@ static int pm_genpd_restore_noirq(struct device *dev) > > pm_genpd_sync_poweron(genpd, true); > >- return genpd_start_dev(genpd, dev, true); >+ return genpd_start_dev(genpd, dev, false); > } > > /** >-- >1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu 2015-10-15 17:02:06, Ulf Hansson wrote: > Measure latency does by itself contribute to an increased latency, thus we > should avoid it when it isn't needed. > > Genpd measures latencies in the system PM phase for the ->start|stop() > callbacks and is thus affecting the system PM suspend/resume time. > Moreover these latencies are validated only at runtime PM suspend/resume. > > To this reasoning, let's decide to leave these measurements out of the > system PM phase. There should be plenty of occasions during runtime PM to > perform these measurements anyway. How much latency does the latency measure cause? Something like 0.000 msec? Pavel
On 21 October 2015 at 12:31, Pavel Machek <pavel@ucw.cz> wrote: > On Thu 2015-10-15 17:02:06, Ulf Hansson wrote: >> Measure latency does by itself contribute to an increased latency, thus we >> should avoid it when it isn't needed. >> >> Genpd measures latencies in the system PM phase for the ->start|stop() >> callbacks and is thus affecting the system PM suspend/resume time. >> Moreover these latencies are validated only at runtime PM suspend/resume. >> >> To this reasoning, let's decide to leave these measurements out of the >> system PM phase. There should be plenty of occasions during runtime PM to >> perform these measurements anyway. > > How much latency does the latency measure cause? Something like 0.000 > msec? Me and Lina did some measurement by hand a couple of weeks ago. If I remember correctly the results where in the range of a couple of us. I will check again and update you with some refreshed data. For system PM the time saved might be negligible, depending on the number of devices that are attached to a genpd and on what level you try to optimize things for. Perhaps this change then becomes more of a policy decision, rather than an a noticeable improvement. I certainly think dealing with device PM QoS constraints should belong to runtime PM and I think it's wrong/useless to do deal with this during system PM. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wednesday, October 21, 2015 02:47:12 PM Ulf Hansson wrote: > On 21 October 2015 at 12:31, Pavel Machek <pavel@ucw.cz> wrote: > > On Thu 2015-10-15 17:02:06, Ulf Hansson wrote: > >> Measure latency does by itself contribute to an increased latency, thus we > >> should avoid it when it isn't needed. > >> > >> Genpd measures latencies in the system PM phase for the ->start|stop() > >> callbacks and is thus affecting the system PM suspend/resume time. > >> Moreover these latencies are validated only at runtime PM suspend/resume. > >> > >> To this reasoning, let's decide to leave these measurements out of the > >> system PM phase. There should be plenty of occasions during runtime PM to > >> perform these measurements anyway. > > > > How much latency does the latency measure cause? Something like 0.000 > > msec? > > Me and Lina did some measurement by hand a couple of weeks ago. If I > remember correctly the results where in the range of a couple of us. I > will check again and update you with some refreshed data. > > For system PM the time saved might be negligible, depending on the > number of devices that are attached to a genpd and on what level you > try to optimize things for. > > Perhaps this change then becomes more of a policy decision, rather > than an a noticeable improvement. I certainly think dealing with > device PM QoS constraints should belong to runtime PM and I think it's > wrong/useless to do deal with this during system PM. Right. It should be used for runtime PM only. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Ulf Hansson <ulf.hansson@linaro.org> writes: > Measure latency does by itself contribute to an increased latency, thus we > should avoid it when it isn't needed. > > Genpd measures latencies in the system PM phase for the ->start|stop() > callbacks and is thus affecting the system PM suspend/resume time. > Moreover these latencies are validated only at runtime PM suspend/resume. > > To this reasoning, let's decide to leave these measurements out of the > system PM phase. There should be plenty of occasions during runtime PM to > perform these measurements anyway. > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Kevin Hilman <khilman@linaro.org> -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 6e1bcde..a1c3ec4 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -90,8 +90,12 @@ static struct generic_pm_domain *dev_to_genpd(struct device *dev) return pd_to_genpd(dev->pm_domain); } -static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev) +static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev, + bool timed) { + if (!timed) + return GENPD_DEV_CALLBACK(genpd, int, stop, dev); + return GENPD_DEV_TIMED_CALLBACK(genpd, int, stop, dev, stop_latency_ns, "stop"); } @@ -434,7 +438,7 @@ static int pm_genpd_runtime_suspend(struct device *dev) if (ret) return ret; - ret = genpd_stop_dev(genpd, dev); + ret = genpd_stop_dev(genpd, dev, true); if (ret) { genpd_restore_dev(genpd, dev, true); return ret; @@ -779,7 +783,7 @@ static int pm_genpd_suspend_noirq(struct device *dev) || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))) return 0; - genpd_stop_dev(genpd, dev); + genpd_stop_dev(genpd, dev, false); /* * Since all of the "noirq" callbacks are executed sequentially, it is @@ -820,7 +824,7 @@ static int pm_genpd_resume_noirq(struct device *dev) pm_genpd_sync_poweron(genpd, true); genpd->suspended_count--; - return genpd_start_dev(genpd, dev, true); + return genpd_start_dev(genpd, dev, false); } /** @@ -928,7 +932,7 @@ static int pm_genpd_freeze_noirq(struct device *dev) if (IS_ERR(genpd)) return -EINVAL; - return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev); + return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev, false); } /** @@ -948,7 +952,8 @@ static int pm_genpd_thaw_noirq(struct device *dev) if (IS_ERR(genpd)) return -EINVAL; - return genpd->suspend_power_off ? 0 : genpd_start_dev(genpd, dev, true); + return genpd->suspend_power_off ? + 0 : genpd_start_dev(genpd, dev, false); } /** @@ -1042,7 +1047,7 @@ static int pm_genpd_restore_noirq(struct device *dev) pm_genpd_sync_poweron(genpd, true); - return genpd_start_dev(genpd, dev, true); + return genpd_start_dev(genpd, dev, false); } /**
Measure latency does by itself contribute to an increased latency, thus we should avoid it when it isn't needed. Genpd measures latencies in the system PM phase for the ->start|stop() callbacks and is thus affecting the system PM suspend/resume time. Moreover these latencies are validated only at runtime PM suspend/resume. To this reasoning, let's decide to leave these measurements out of the system PM phase. There should be plenty of occasions during runtime PM to perform these measurements anyway. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- drivers/base/power/domain.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)