From: Lina Iyer <lina.iyer@linaro.org> To: Stephen Boyd <sboyd@codeaurora.org> Cc: ulf.hansson@linaro.org, khilman@kernel.org, rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, geert@linux-m68k.org, k.kozlowski@samsung.com, msivasub@codeaurora.org, agross@codeaurora.org, linux-arm-msm@vger.kernel.org, lorenzo.pieralisi@arm.com, ahaslam@baylibre.com, mtitinger@baylibre.com Subject: Re: [RFC v2 07/12] PM / cpu_domains: Add PM Domain governor for CPUs Date: Tue, 1 Mar 2016 12:32:20 -0700 [thread overview] Message-ID: <20160301193220.GN1440@linaro.org> (raw) In-Reply-To: <20160226193338.GY28849@codeaurora.org> On Fri, Feb 26 2016 at 12:33 -0700, Stephen Boyd wrote: >On 02/12, Lina Iyer wrote: >> @@ -52,6 +55,76 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d) >> return res; >> } >> >> +static bool cpu_pd_down_ok(struct dev_pm_domain *pd) >> +{ >> + struct generic_pm_domain *genpd = pd_to_genpd(pd); >> + struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd); >> + int qos = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); >> + u64 sleep_ns; >> + ktime_t earliest, next_wakeup; >> + int cpu; >> + int i; >> + >> + /* Reset the last set genpd state, default to index 0 */ >> + genpd->state_idx = 0; >> + >> + /* We dont want to power down, if QoS is 0 */ >> + if (!qos) >> + return false; >> + >> + /* >> + * Find the sleep time for the cluster. >> + * The time between now and the first wake up of any CPU that >> + * are in this domain hierarchy is the time available for the >> + * domain to be idle. >> + */ >> + earliest = ktime_set(KTIME_SEC_MAX, 0); >> + for_each_cpu_and(cpu, cpu_pd->cpus, cpu_online_mask) { > >We're not worried about hotplug happening in parallel because >preemption is disabled here? > Nope. Hotplug on the same domain or in its hierarchy will be waiting on the domain lock to released before becoming online. Any other domain is not of concern for this domain governor. If a core was hotplugged out while this is happening, then we may risk making an premature wake up decision, which would happen either way if we lock hotplug here. >> + next_wakeup = tick_nohz_get_next_wakeup(cpu); >> + if (earliest.tv64 > next_wakeup.tv64) > > if (ktime_before(next_wakeup, earliest)) > >> + earliest = next_wakeup; >> + } >> + >> + sleep_ns = ktime_to_ns(ktime_sub(earliest, ktime_get())); >> + if (sleep_ns <= 0) >> + return false; >> + >> + /* >> + * Find the deepest sleep state that satisfies the residency >> + * requirement and the QoS constraint >> + */ >> + for (i = genpd->state_count - 1; i >= 0; i--) { >> + u64 state_sleep_ns; >> + >> + state_sleep_ns = genpd->states[i].power_off_latency_ns + >> + genpd->states[i].power_on_latency_ns + >> + genpd->states[i].residency_ns; >> + >> + /* >> + * If we cant sleep to save power in the state, move on > >s/cant/can't/ > argh. Fixed. >> + * to the next lower idle state. >> + */ >> + if (state_sleep_ns > sleep_ns) >> + continue; >> + >> + /* >> + * We also dont want to sleep more than we should to > >s/dont/don't/ > Done >> + * gaurantee QoS. >> + */ >> + if (state_sleep_ns < (qos * NSEC_PER_USEC)) > >Maybe we should make qos into qos_ns? Presumably the compiler >would hoist out the multiplication here, but it doesn't hurt to >do it explicitly. > Okay >> + break; >> + } >> + >> + if (i >= 0) >> + genpd->state_idx = i; >> + >> + return (i >= 0) ? true : false; > >Just return i >= 0? > Ok Thanks, Lina >-- >Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, >a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: lina.iyer@linaro.org (Lina Iyer) To: linux-arm-kernel@lists.infradead.org Subject: [RFC v2 07/12] PM / cpu_domains: Add PM Domain governor for CPUs Date: Tue, 1 Mar 2016 12:32:20 -0700 [thread overview] Message-ID: <20160301193220.GN1440@linaro.org> (raw) In-Reply-To: <20160226193338.GY28849@codeaurora.org> On Fri, Feb 26 2016 at 12:33 -0700, Stephen Boyd wrote: >On 02/12, Lina Iyer wrote: >> @@ -52,6 +55,76 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d) >> return res; >> } >> >> +static bool cpu_pd_down_ok(struct dev_pm_domain *pd) >> +{ >> + struct generic_pm_domain *genpd = pd_to_genpd(pd); >> + struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd); >> + int qos = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); >> + u64 sleep_ns; >> + ktime_t earliest, next_wakeup; >> + int cpu; >> + int i; >> + >> + /* Reset the last set genpd state, default to index 0 */ >> + genpd->state_idx = 0; >> + >> + /* We dont want to power down, if QoS is 0 */ >> + if (!qos) >> + return false; >> + >> + /* >> + * Find the sleep time for the cluster. >> + * The time between now and the first wake up of any CPU that >> + * are in this domain hierarchy is the time available for the >> + * domain to be idle. >> + */ >> + earliest = ktime_set(KTIME_SEC_MAX, 0); >> + for_each_cpu_and(cpu, cpu_pd->cpus, cpu_online_mask) { > >We're not worried about hotplug happening in parallel because >preemption is disabled here? > Nope. Hotplug on the same domain or in its hierarchy will be waiting on the domain lock to released before becoming online. Any other domain is not of concern for this domain governor. If a core was hotplugged out while this is happening, then we may risk making an premature wake up decision, which would happen either way if we lock hotplug here. >> + next_wakeup = tick_nohz_get_next_wakeup(cpu); >> + if (earliest.tv64 > next_wakeup.tv64) > > if (ktime_before(next_wakeup, earliest)) > >> + earliest = next_wakeup; >> + } >> + >> + sleep_ns = ktime_to_ns(ktime_sub(earliest, ktime_get())); >> + if (sleep_ns <= 0) >> + return false; >> + >> + /* >> + * Find the deepest sleep state that satisfies the residency >> + * requirement and the QoS constraint >> + */ >> + for (i = genpd->state_count - 1; i >= 0; i--) { >> + u64 state_sleep_ns; >> + >> + state_sleep_ns = genpd->states[i].power_off_latency_ns + >> + genpd->states[i].power_on_latency_ns + >> + genpd->states[i].residency_ns; >> + >> + /* >> + * If we cant sleep to save power in the state, move on > >s/cant/can't/ > argh. Fixed. >> + * to the next lower idle state. >> + */ >> + if (state_sleep_ns > sleep_ns) >> + continue; >> + >> + /* >> + * We also dont want to sleep more than we should to > >s/dont/don't/ > Done >> + * gaurantee QoS. >> + */ >> + if (state_sleep_ns < (qos * NSEC_PER_USEC)) > >Maybe we should make qos into qos_ns? Presumably the compiler >would hoist out the multiplication here, but it doesn't hurt to >do it explicitly. > Okay >> + break; >> + } >> + >> + if (i >= 0) >> + genpd->state_idx = i; >> + >> + return (i >= 0) ? true : false; > >Just return i >= 0? > Ok Thanks, Lina >-- >Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, >a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-03-01 19:32 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-02-12 20:50 [RFC v2 00/12] PM: SoC idle support using PM domains Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 01/12] PM / Domains: Abstract genpd locking Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 18:08 ` Stephen Boyd 2016-02-26 18:08 ` Stephen Boyd 2016-03-01 16:55 ` Lina Iyer 2016-03-01 16:55 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 02/12] PM / Domains: Support IRQ safe PM domains Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 18:17 ` Stephen Boyd 2016-02-26 18:17 ` Stephen Boyd 2016-03-01 17:44 ` Lina Iyer 2016-03-01 17:44 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-17 23:38 ` Lina Iyer 2016-02-17 23:38 ` Lina Iyer 2016-02-18 17:29 ` [BUG FIX] PM / cpu_domains: Check for NULL callbacks Lina Iyer 2016-02-18 17:29 ` Lina Iyer 2016-02-18 17:46 ` Rafael J. Wysocki 2016-02-18 17:46 ` Rafael J. Wysocki 2016-02-18 22:51 ` Lina Iyer 2016-02-18 22:51 ` Lina Iyer 2016-02-26 19:10 ` [RFC v2 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters Stephen Boyd 2016-02-26 19:10 ` Stephen Boyd 2016-03-01 18:00 ` Lina Iyer 2016-03-01 18:00 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 04/12] ARM: cpuidle: Add runtime PM support for CPUs Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 18:24 ` Stephen Boyd 2016-02-26 18:24 ` Stephen Boyd 2016-03-01 18:36 ` Lina Iyer 2016-03-01 18:36 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 05/12] timer: Export next wake up of a CPU Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 06/12] PM / cpu_domains: Record CPUs that are part of the domain Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 19:20 ` Stephen Boyd 2016-02-26 19:20 ` Stephen Boyd 2016-03-01 19:24 ` Lina Iyer 2016-03-01 19:24 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 07/12] PM / cpu_domains: Add PM Domain governor for CPUs Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 19:33 ` Stephen Boyd 2016-02-26 19:33 ` Stephen Boyd 2016-03-01 19:32 ` Lina Iyer [this message] 2016-03-01 19:32 ` Lina Iyer 2016-03-01 19:35 ` Stephen Boyd 2016-03-01 19:35 ` Stephen Boyd 2016-02-12 20:50 ` [RFC v2 08/12] Documentation / cpu_domains: Describe CPU PM domains setup and governor Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 19:43 ` Stephen Boyd 2016-02-26 19:43 ` Stephen Boyd 2016-03-01 19:36 ` Lina Iyer 2016-03-01 19:36 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 09/12] drivers: firmware: psci: Allow OS Initiated suspend mode Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 10/12] ARM64: psci: Support cluster idle states for OS-Initiated Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 11/12] ARM64: dts: Add PSCI cpuidle support for MSM8916 Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-12 20:50 ` [RFC v2 12/12] ARM64: dts: Define CPU power domain " Lina Iyer 2016-02-12 20:50 ` Lina Iyer 2016-02-26 19:50 ` Stephen Boyd 2016-02-26 19:50 ` Stephen Boyd 2016-03-01 19:41 ` Lina Iyer 2016-03-01 19:41 ` Lina Iyer
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