Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752247AbbKJJma (ORCPT ); Tue, 10 Nov 2015 04:42:30 -0500 Received: from mail-yk0-f175.google.com ([209.85.160.175]:36777 "EHLO mail-yk0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751832AbbKJJmZ (ORCPT ); Tue, 10 Nov 2015 04:42:25 -0500 MIME-Version: 1.0 In-Reply-To: <1445347589-5626-4-git-send-email-ahaslam@baylibre.com> References: <1445347589-5626-1-git-send-email-ahaslam@baylibre.com> <1445347589-5626-4-git-send-email-ahaslam@baylibre.com> Date: Tue, 10 Nov 2015 17:42:25 +0800 Message-ID: Subject: Re: [PATCH v10 3/6] PM / Domains: make governor select deepest state From: Zhaoyang Huang To: ahaslam@baylibre.com Cc: Kevin Hilman , Ulf Hansson , Lina Iyer , geert@glider.be, k.kozlowski.k@gmail.com, rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, bcousson@baylibre.com, mturquette@baylibre.com, Axel Haslam Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6378 Lines: 154 On 20 October 2015 at 21:26, wrote: > From: Axel Haslam > > Now that the structures of genpd can support multiple state definitions, > add the logic in the governor to select the deepest possible state when > powering down. > > For this, create the new function power_down_ok_for_state which will test > if a particular state will not violate the devices and sub-domains > constraints. > > default_power_down_ok is modified to try each state starting from the > deepest until a valid state is found or there are no more states to test. > > the resulting state will be valid until there are latency or constraint > changes, thus, we can avoid looping every power_down, and use the cached > results instead. > > Signed-off-by: Axel Haslam > --- > drivers/base/power/domain_governor.c | 75 +++++++++++++++++++++--------------- > 1 file changed, 45 insertions(+), 30 deletions(-) > > diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c > index bf3ac68..aab2b32 100644 > --- a/drivers/base/power/domain_governor.c > +++ b/drivers/base/power/domain_governor.c > @@ -100,7 +100,8 @@ static bool default_stop_ok(struct device *dev) > * > * This routine must be executed under the PM domain's lock. > */ > -static bool default_power_down_ok(struct dev_pm_domain *pd) > +static bool power_down_ok_for_state(struct dev_pm_domain *pd, > + unsigned int state) > { > struct generic_pm_domain *genpd = pd_to_genpd(pd); > struct gpd_link *link; > @@ -108,31 +109,9 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) > s64 min_off_time_ns; > s64 off_on_time_ns; > > - if (genpd->max_off_time_changed) { > - struct gpd_link *link; > + off_on_time_ns = genpd->states[state].power_off_latency_ns + > + genpd->states[state].power_on_latency_ns; > > - /* > - * We have to invalidate the cached results for the masters, so > - * use the observation that default_power_down_ok() is not > - * going to be called for any master until this instance > - * returns. > - */ > - list_for_each_entry(link, &genpd->slave_links, slave_node) > - link->master->max_off_time_changed = true; > - > - genpd->max_off_time_changed = false; > - genpd->cached_power_down_ok = false; > - genpd->max_off_time_ns = -1; > - } else { > - return genpd->cached_power_down_ok; > - } > - > - /* > - * Use the only available state, until multiple state support is added > - * to the governor. > - */ > - off_on_time_ns = genpd->states[0].power_off_latency_ns + > - genpd->states[0].power_on_latency_ns; > > min_off_time_ns = -1; > /* > @@ -195,8 +174,6 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) > min_off_time_ns = constraint_ns; > } > > - genpd->cached_power_down_ok = true; > - > /* > * If the computed minimum device off time is negative, there are no > * latency constraints, so the domain can spend arbitrary time in the > @@ -209,14 +186,52 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) > * The difference between the computed minimum subdomain or device off > * time and the time needed to turn the domain on is the maximum > * theoretical time this domain can spend in the "off" state. > - * Use the only available state, until multiple state support is added > - * to the governor. > */ > genpd->max_off_time_ns = min_off_time_ns - > - genpd->states[0].power_on_latency_ns; > + genpd->states[state].power_on_latency_ns; > return true; > } [question]: Does it mean that the sleep level is just decided by comparing the pre-configure on_off time with the gpd_timing_data? How about the next timer event which affect the sleep depth on cpuidle framework? > > +static bool default_power_down_ok(struct dev_pm_domain *pd) > +{ > + struct generic_pm_domain *genpd = pd_to_genpd(pd); > + unsigned int last_state_idx = genpd->state_count - 1; > + struct gpd_link *link; > + bool retval = false; > + unsigned int i; > + > + /* > + * if there was no change on max_off_time, we can return the > + * cached value and we dont need to find a new target_state > + */ > + if (!genpd->max_off_time_changed) > + return genpd->cached_power_down_ok; > + > + /* > + * We have to invalidate the cached results for the masters, so > + * use the observation that default_power_down_ok() is not > + * going to be called for any master until this instance > + * returns. > + */ > + list_for_each_entry(link, &genpd->slave_links, slave_node) > + link->master->max_off_time_changed = true; > + > + genpd->max_off_time_ns = -1; > + genpd->max_off_time_changed = false; > + > + /* find a state to power down to, starting from the deepest */ > + for (i = 0; i < genpd->state_count; i++) { > + if (power_down_ok_for_state(pd, last_state_idx - i)) { > + genpd->state_idx = last_state_idx - i; > + retval = true; > + break; > + } > + } > + > + genpd->cached_power_down_ok = retval; > + return retval; > +} > + > static bool always_on_power_down_ok(struct dev_pm_domain *domain) > { > return false; [question]How the TICK_NOHZ treated if we substitute cpuidle framework with this one? > -- > 2.4.5 > > -- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/