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authorViresh Kumar <viresh.kumar@linaro.org>2020-06-23 15:49:40 +0530
committerViresh Kumar <viresh.kumar@linaro.org>2021-07-01 07:32:14 +0530
commit1eb5dde674f57b1a1918dab33f09e35cdd64eb07 (patch)
tree49bd7275d8fb848e7a933bf11ebcbd7dc227c6e0
parent83150f5d05f065fb5c12c612f119015cabdcc124 (diff)
cpufreq: CPPC: Add support for frequency invariance
The Frequency Invariance Engine (FIE) is providing a frequency scaling correction factor that helps achieve more accurate load-tracking. Normally, this scaling factor can be obtained directly with the help of the cpufreq drivers as they know the exact frequency the hardware is running at. But that isn't the case for CPPC cpufreq driver. Another way of obtaining that is using the arch specific counter support, which is already present in kernel, but that hardware is optional for platforms. This patch updates the CPPC driver to register itself with the topology core to provide its own implementation (cppc_scale_freq_tick()) of topology_scale_freq_tick() which gets called by the scheduler on every tick. Note that the arch specific counters have higher priority than CPPC counters, if available, though the CPPC driver doesn't need to have any special handling for that. On an invocation of cppc_scale_freq_tick(), we schedule an irq work (since we reach here from hard-irq context), which then schedules a normal work item and cppc_scale_freq_workfn() updates the per_cpu arch_freq_scale variable based on the counter updates since the last tick. To allow platforms to disable this CPPC counter-based frequency invariance support, this is all done under CONFIG_ACPI_CPPC_CPUFREQ_FIE, which is enabled by default. This also exports sched_setattr_nocheck() as the CPPC driver can be built as a module. Cc: linux-acpi@vger.kernel.org Tested-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com> Tested-by: Qian Cai <quic_qiancai@quicinc.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
-rw-r--r--drivers/cpufreq/Kconfig.arm10
-rw-r--r--drivers/cpufreq/cppc_cpufreq.c252
-rw-r--r--include/linux/arch_topology.h1
-rw-r--r--kernel/sched/core.c1
4 files changed, 251 insertions, 13 deletions
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index e65e0a43be64..a5c5f70acfc9 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -19,6 +19,16 @@ config ACPI_CPPC_CPUFREQ
If in doubt, say N.
+config ACPI_CPPC_CPUFREQ_FIE
+ bool "Frequency Invariance support for CPPC cpufreq driver"
+ depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY
+ default y
+ help
+ This extends frequency invariance support in the CPPC cpufreq driver,
+ by using CPPC delivered and reference performance counters.
+
+ If in doubt, say N.
+
config ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM
tristate "Allwinner nvmem based SUN50I CPUFreq driver"
depends on ARCH_SUNXI
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 4a7f0f9b8c60..d4c27022b9c9 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -10,14 +10,18 @@
#define pr_fmt(fmt) "CPPC Cpufreq:" fmt
+#include <linux/arch_topology.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/dmi.h>
+#include <linux/irq_work.h>
+#include <linux/kthread.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
+#include <uapi/linux/sched/types.h>
#include <asm/unaligned.h>
@@ -57,6 +61,216 @@ static struct cppc_workaround_oem_info wa_info[] = {
}
};
+#ifdef CONFIG_ACPI_CPPC_CPUFREQ_FIE
+
+/* Frequency invariance support */
+struct cppc_freq_invariance {
+ int cpu;
+ struct irq_work irq_work;
+ struct kthread_work work;
+ struct cppc_perf_fb_ctrs prev_perf_fb_ctrs;
+ struct cppc_cpudata *cpu_data;
+};
+
+static DEFINE_PER_CPU(struct cppc_freq_invariance, cppc_freq_inv);
+static struct kthread_worker *kworker_fie;
+
+static struct cpufreq_driver cppc_cpufreq_driver;
+static unsigned int hisi_cppc_cpufreq_get_rate(unsigned int cpu);
+static int cppc_perf_from_fbctrs(struct cppc_cpudata *cpu_data,
+ struct cppc_perf_fb_ctrs *fb_ctrs_t0,
+ struct cppc_perf_fb_ctrs *fb_ctrs_t1);
+
+/**
+ * cppc_scale_freq_workfn - CPPC arch_freq_scale updater for frequency invariance
+ * @work: The work item.
+ *
+ * The CPPC driver register itself with the topology core to provide its own
+ * implementation (cppc_scale_freq_tick()) of topology_scale_freq_tick() which
+ * gets called by the scheduler on every tick.
+ *
+ * Note that the arch specific counters have higher priority than CPPC counters,
+ * if available, though the CPPC driver doesn't need to have any special
+ * handling for that.
+ *
+ * On an invocation of cppc_scale_freq_tick(), we schedule an irq work (since we
+ * reach here from hard-irq context), which then schedules a normal work item
+ * and cppc_scale_freq_workfn() updates the per_cpu arch_freq_scale variable
+ * based on the counter updates since the last tick.
+ */
+static void cppc_scale_freq_workfn(struct kthread_work *work)
+{
+ struct cppc_freq_invariance *cppc_fi;
+ struct cppc_perf_fb_ctrs fb_ctrs = {0};
+ struct cppc_cpudata *cpu_data;
+ unsigned long local_freq_scale;
+ u64 perf;
+
+ cppc_fi = container_of(work, struct cppc_freq_invariance, work);
+ cpu_data = cppc_fi->cpu_data;
+
+ if (cppc_get_perf_ctrs(cppc_fi->cpu, &fb_ctrs)) {
+ pr_warn("%s: failed to read perf counters\n", __func__);
+ return;
+ }
+
+ perf = cppc_perf_from_fbctrs(cpu_data, &cppc_fi->prev_perf_fb_ctrs,
+ &fb_ctrs);
+ cppc_fi->prev_perf_fb_ctrs = fb_ctrs;
+
+ perf <<= SCHED_CAPACITY_SHIFT;
+ local_freq_scale = div64_u64(perf, cpu_data->perf_caps.highest_perf);
+
+ /* This can happen due to counter's overflow */
+ if (unlikely(local_freq_scale > 1024))
+ local_freq_scale = 1024;
+
+ per_cpu(arch_freq_scale, cppc_fi->cpu) = local_freq_scale;
+}
+
+static void cppc_irq_work(struct irq_work *irq_work)
+{
+ struct cppc_freq_invariance *cppc_fi;
+
+ cppc_fi = container_of(irq_work, struct cppc_freq_invariance, irq_work);
+ kthread_queue_work(kworker_fie, &cppc_fi->work);
+}
+
+static void cppc_scale_freq_tick(void)
+{
+ struct cppc_freq_invariance *cppc_fi = &per_cpu(cppc_freq_inv, smp_processor_id());
+
+ /*
+ * cppc_get_perf_ctrs() can potentially sleep, call that from the right
+ * context.
+ */
+ irq_work_queue(&cppc_fi->irq_work);
+}
+
+static struct scale_freq_data cppc_sftd = {
+ .source = SCALE_FREQ_SOURCE_CPPC,
+ .set_freq_scale = cppc_scale_freq_tick,
+};
+
+static void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy)
+{
+ struct cppc_freq_invariance *cppc_fi;
+ int cpu, ret;
+
+ if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
+ return;
+
+ for_each_cpu(cpu, policy->cpus) {
+ cppc_fi = &per_cpu(cppc_freq_inv, cpu);
+ cppc_fi->cpu = cpu;
+ cppc_fi->cpu_data = policy->driver_data;
+ kthread_init_work(&cppc_fi->work, cppc_scale_freq_workfn);
+ init_irq_work(&cppc_fi->irq_work, cppc_irq_work);
+
+ ret = cppc_get_perf_ctrs(cpu, &cppc_fi->prev_perf_fb_ctrs);
+ if (ret) {
+ pr_warn("%s: failed to read perf counters for cpu:%d: %d\n",
+ __func__, cpu, ret);
+
+ /*
+ * Don't abort if the CPU was offline while the driver
+ * was getting registered.
+ */
+ if (cpu_online(cpu))
+ return;
+ }
+ }
+
+ /* Register for freq-invariance */
+ topology_set_scale_freq_source(&cppc_sftd, policy->cpus);
+}
+
+/*
+ * We free all the resources on policy's removal and not on CPU removal as the
+ * irq-work are per-cpu and the hotplug core takes care of flushing the pending
+ * irq-works (hint: smpcfd_dying_cpu()) on CPU hotplug. Even if the kthread-work
+ * fires on another CPU after the concerned CPU is removed, it won't harm.
+ *
+ * We just need to make sure to remove them all on policy->exit().
+ */
+static void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy)
+{
+ struct cppc_freq_invariance *cppc_fi;
+ int cpu;
+
+ if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
+ return;
+
+ /* policy->cpus will be empty here, use related_cpus instead */
+ topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC, policy->related_cpus);
+
+ for_each_cpu(cpu, policy->related_cpus) {
+ cppc_fi = &per_cpu(cppc_freq_inv, cpu);
+ irq_work_sync(&cppc_fi->irq_work);
+ kthread_cancel_work_sync(&cppc_fi->work);
+ }
+}
+
+static void __init cppc_freq_invariance_init(void)
+{
+ struct sched_attr attr = {
+ .size = sizeof(struct sched_attr),
+ .sched_policy = SCHED_DEADLINE,
+ .sched_nice = 0,
+ .sched_priority = 0,
+ /*
+ * Fake (unused) bandwidth; workaround to "fix"
+ * priority inheritance.
+ */
+ .sched_runtime = 1000000,
+ .sched_deadline = 10000000,
+ .sched_period = 10000000,
+ };
+ int ret;
+
+ if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
+ return;
+
+ kworker_fie = kthread_create_worker(0, "cppc_fie");
+ if (IS_ERR(kworker_fie))
+ return;
+
+ ret = sched_setattr_nocheck(kworker_fie->task, &attr);
+ if (ret) {
+ pr_warn("%s: failed to set SCHED_DEADLINE: %d\n", __func__,
+ ret);
+ kthread_destroy_worker(kworker_fie);
+ return;
+ }
+}
+
+static void cppc_freq_invariance_exit(void)
+{
+ if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
+ return;
+
+ kthread_destroy_worker(kworker_fie);
+ kworker_fie = NULL;
+}
+
+#else
+static inline void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy)
+{
+}
+
+static inline void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy)
+{
+}
+
+static inline void cppc_freq_invariance_init(void)
+{
+}
+
+static inline void cppc_freq_invariance_exit(void)
+{
+}
+#endif /* CONFIG_ACPI_CPPC_CPUFREQ_FIE */
+
/* Callback function used to retrieve the max frequency from DMI */
static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
{
@@ -341,6 +555,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
goto out;
}
+ cppc_cpufreq_cpu_fie_init(policy);
return 0;
out:
@@ -355,6 +570,8 @@ static int cppc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
unsigned int cpu = policy->cpu;
int ret;
+ cppc_cpufreq_cpu_fie_exit(policy);
+
cpu_data->perf_ctrls.desired_perf = caps->lowest_perf;
ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);
@@ -374,12 +591,12 @@ static inline u64 get_delta(u64 t1, u64 t0)
return (u32)t1 - (u32)t0;
}
-static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu_data,
- struct cppc_perf_fb_ctrs *fb_ctrs_t0,
- struct cppc_perf_fb_ctrs *fb_ctrs_t1)
+static int cppc_perf_from_fbctrs(struct cppc_cpudata *cpu_data,
+ struct cppc_perf_fb_ctrs *fb_ctrs_t0,
+ struct cppc_perf_fb_ctrs *fb_ctrs_t1)
{
u64 delta_reference, delta_delivered;
- u64 reference_perf, delivered_perf;
+ u64 reference_perf;
reference_perf = fb_ctrs_t0->reference_perf;
@@ -388,14 +605,11 @@ static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu_data,
delta_delivered = get_delta(fb_ctrs_t1->delivered,
fb_ctrs_t0->delivered);
- /* Check to avoid divide-by zero */
- if (delta_reference || delta_delivered)
- delivered_perf = (reference_perf * delta_delivered) /
- delta_reference;
- else
- delivered_perf = cpu_data->perf_ctrls.desired_perf;
+ /* Check to avoid divide-by zero and invalid delivered_perf */
+ if (!delta_reference || !delta_delivered)
+ return cpu_data->perf_ctrls.desired_perf;
- return cppc_cpufreq_perf_to_khz(cpu_data, delivered_perf);
+ return (reference_perf * delta_delivered) / delta_reference;
}
static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
@@ -403,6 +617,7 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
struct cppc_cpudata *cpu_data = policy->driver_data;
+ u64 delivered_perf;
int ret;
cpufreq_cpu_put(policy);
@@ -417,7 +632,10 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
if (ret)
return ret;
- return cppc_get_rate_from_fbctrs(cpu_data, &fb_ctrs_t0, &fb_ctrs_t1);
+ delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0,
+ &fb_ctrs_t1);
+
+ return cppc_cpufreq_perf_to_khz(cpu_data, delivered_perf);
}
static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
@@ -518,14 +736,21 @@ static void cppc_check_hisi_workaround(void)
static int __init cppc_cpufreq_init(void)
{
+ int ret;
+
if ((acpi_disabled) || !acpi_cpc_valid())
return -ENODEV;
INIT_LIST_HEAD(&cpu_data_list);
cppc_check_hisi_workaround();
+ cppc_freq_invariance_init();
- return cpufreq_register_driver(&cppc_cpufreq_driver);
+ ret = cpufreq_register_driver(&cppc_cpufreq_driver);
+ if (ret)
+ cppc_freq_invariance_exit();
+
+ return ret;
}
static inline void free_cpu_data(void)
@@ -543,6 +768,7 @@ static inline void free_cpu_data(void)
static void __exit cppc_cpufreq_exit(void)
{
cpufreq_unregister_driver(&cppc_cpufreq_driver);
+ cppc_freq_invariance_exit();
free_cpu_data();
}
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 11e555cfaecb..f180240dc95f 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -37,6 +37,7 @@ bool topology_scale_freq_invariant(void);
enum scale_freq_source {
SCALE_FREQ_SOURCE_CPUFREQ = 0,
SCALE_FREQ_SOURCE_ARCH,
+ SCALE_FREQ_SOURCE_CPPC,
};
struct scale_freq_data {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cf16f8fda9a6..2d9ff40f4661 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7182,6 +7182,7 @@ int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
{
return __sched_setscheduler(p, attr, false, true);
}
+EXPORT_SYMBOL_GPL(sched_setattr_nocheck);
/**
* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.