Messages in this thread Patch in this message | | | Date | Mon, 17 Aug 2015 16:59:29 +0100 | From | Dietmar Eggemann <> | Subject | Re: [RFCv5 PATCH 01/46] arm: Frequency invariant scheduler load-tracking support |
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Hi Vincent,
On 03/08/15 10:22, Vincent Guittot wrote: > Hi Morten, > > > On 7 July 2015 at 20:23, Morten Rasmussen <morten.rasmussen@arm.com> wrote: >> From: Morten Rasmussen <Morten.Rasmussen@arm.com> >> > > [snip] > >> - >> #endif >> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c >> index 08b7847..9c09e6e 100644 >> --- a/arch/arm/kernel/topology.c >> +++ b/arch/arm/kernel/topology.c >> @@ -169,6 +169,23 @@ static void update_cpu_capacity(unsigned int cpu) >> cpu, arch_scale_cpu_capacity(NULL, cpu)); >> } >> >> +/* >> + * Scheduler load-tracking scale-invariance >> + * >> + * Provides the scheduler with a scale-invariance correction factor that >> + * compensates for frequency scaling (arch_scale_freq_capacity()). The scaling >> + * factor is updated in smp.c >> + */ >> +unsigned long arm_arch_scale_freq_capacity(struct sched_domain *sd, int cpu) >> +{ >> + unsigned long curr = atomic_long_read(&per_cpu(cpu_freq_capacity, cpu)); > > access to cpu_freq_capacity to should be put under #ifdef CONFIG_CPU_FREQ.
True, in case we keep everything related to frequency scaling under CONFIG_CPU_FREQ, then we should also put the #define arch_scale_freq_capacity arm_arch_scale_freq_capacity in topology.h under CONFIG_CPU_FREQ.
> Why haven't you moved arm_arch_scale_freq_capacity in smp.c as > everything else for frequency in-variance is already in this file ? > This should also enable you to remove > DECLARE_PER_CPU(atomic_long_t, cpu_freq_capacity); from topology.h
True, arm_arch_scale_freq_capacity() should be in smp.c so we don't have to export cpu_freq_capacity which btw. does not have to be a atomic.
OTHA, we could also put the whole 'Frequency Invariance Engine' into cpufreq.c as cpufreq_scale_freq_capacity() and let the interested ARCH do a #include <linux/cpufreq.h> #define arch_scale_freq_capacity cpufreq_scale_freq_capacity This would allow us to implement this 'Frequency Invariance Engine' only once and not couple of times for different ARCHs.
Something like this: (only compile tested on ARM64 w/ and w/o CONFIG_CPU_FREQ)
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h index a8a69a1f3c4c..f25341170749 100644 --- a/arch/arm64/include/asm/topology.h +++ b/arch/arm64/include/asm/topology.h @@ -4,6 +4,7 @@ #ifdef CONFIG_SMP #include <linux/cpumask.h> +#include <linux/cpufreq.h> struct cpu_topology { int thread_id; @@ -26,9 +27,7 @@ const struct cpumask *cpu_coregroup_mask(int cpu); struct sched_domain; #ifdef CONFIG_CPU_FREQ -#define arch_scale_freq_capacity arm_arch_scale_freq_capacity -extern -unsigned long arm_arch_scale_freq_capacity(struct sched_domain *sd, int cpu); +#define arch_scale_freq_capacity cpufreq_scale_freq_capacity #endif #define arch_scale_cpu_capacity arm_arch_scale_cpu_capacity diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index b612411655f9..97f4391d0f55 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2400,6 +2400,12 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb, return NOTIFY_OK; } +unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu) +{ + return 1024; /* Implementation missing !!! */ +} +EXPORT_SYMBOL(cpufreq_scale_freq_capacity); + static struct notifier_block __refdata cpufreq_cpu_notifier = { .notifier_call = cpufreq_cpu_callback, }; diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 29ad97c34fd5..a4516d53a3cc 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -604,4 +604,11 @@ unsigned int cpufreq_generic_get(unsigned int cpu); int cpufreq_generic_init(struct cpufreq_policy *policy, struct cpufreq_frequency_table *table, unsigned int transition_latency); +/* + * In case we delete unused sd pointer in arch_scale_freq_capacity() + * [kernel/sched/sched.h] this can become: + * unsigned long cpufreq_scale_freq_capacity(int cpu); + */ +struct sched_domain; +unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu);
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