Re: [PATCH V5 2/2] cpufreq: CPPC: Add support for frequency invariance
On Tue, 9 Mar 2021 at 16:10, Ionela Voinescu wrote:
>
> Hey,
>
> On Monday 01 Mar 2021 at 12:21:18 (+0530), Viresh Kumar wrote:
> > 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
> > freq_scale variable based on the counter updates since the last tick.
> >
> > To allow platforms to disable frequency invariance support if they want,
>^
>this CPPC counter-based frequency invariance
>support..
>
> (disabling this config will not disable cpufreq or arch counter-based FIE)
>
> > 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: Ionela Voinescu
> > Cc: linux-a...@vger.kernel.org
> > Signed-off-by: Viresh Kumar
> > ---
> > drivers/cpufreq/Kconfig.arm| 9 ++
> > drivers/cpufreq/cppc_cpufreq.c | 244 +++--
> > include/linux/arch_topology.h | 1 +
> > kernel/sched/core.c| 1 +
> > 4 files changed, 243 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> > index e65e0a43be64..a3e2d6dfea70 100644
> > --- a/drivers/cpufreq/Kconfig.arm
> > +++ b/drivers/cpufreq/Kconfig.arm
> > @@ -19,6 +19,15 @@ 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
>
> It also depends on GENERIC_ARCH_TOPOLOGY.
>
> > + default y
> > + help
> > + This enables frequency invariance support for CPPC cpufreq driver.
>
> s//based on CPPC counters.
>
> .. or more detailed: 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 8a482c434ea6..c4580a37a1b1 100644
> > --- a/drivers/cpufreq/cppc_cpufreq.c
> > +++ b/drivers/cpufreq/cppc_cpufreq.c
> [..]
> > +static void cppc_freq_invariance_policy_init(struct cpufreq_policy *policy,
> > + struct cppc_cpudata *cpu_data)
> > +{
> > + struct cppc_freq_invariance *cppc_fi;
> > + int i;
> > +
> > + if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
> > + return;
> > +
> > + for_each_cpu(i, policy->cpus) {
> > + cppc_fi = _cpu(cppc_freq_inv, i);
> > + cppc_fi->cpu = i;
> > + cppc_fi->cpu_data = cpu_data;
> > + kthread_init_work(_fi->work, cppc_scale_freq_workfn);
> > + init_irq_work(_fi->irq_work, cppc_irq_work);
> > + }
> > +}
> > +
> > +static void cppc_freq_invariance_exit(void)
> > +{
> > + struct cppc_freq_invariance *cppc_fi;
> > + int i;
> > +
> > + if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
> > + return;
> > +
> > + topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC,
> > cpu_present_mask);
> > +
> > + for_each_possible_cpu(i) {
> > + cppc_fi = _cpu(cppc_freq_inv, i);
> > + irq_work_sync(_fi->irq_work);
> > + }
> > +
> > + kthread_destroy_worker(kworker_fie);
> > + kworker_fie = NULL;
> > +}
> > +
> > +static void __init cppc_freq_invariance_init(void)
> > +{
> > + struct cppc_perf_fb_ctrs fb_ctrs = {0};
> > + struct cppc_freq_invariance *cppc_fi;
> > + struct sched_attr attr
Re: [PATCH V5 2/2] cpufreq: CPPC: Add support for frequency invariance
Hey,
On Monday 01 Mar 2021 at 12:21:18 (+0530), Viresh Kumar wrote:
> 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
> freq_scale variable based on the counter updates since the last tick.
>
> To allow platforms to disable frequency invariance support if they want,
^
this CPPC counter-based frequency invariance
support..
(disabling this config will not disable cpufreq or arch counter-based FIE)
> 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: Ionela Voinescu
> Cc: linux-a...@vger.kernel.org
> Signed-off-by: Viresh Kumar
> ---
> drivers/cpufreq/Kconfig.arm| 9 ++
> drivers/cpufreq/cppc_cpufreq.c | 244 +++--
> include/linux/arch_topology.h | 1 +
> kernel/sched/core.c| 1 +
> 4 files changed, 243 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index e65e0a43be64..a3e2d6dfea70 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -19,6 +19,15 @@ 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
It also depends on GENERIC_ARCH_TOPOLOGY.
> + default y
> + help
> + This enables frequency invariance support for CPPC cpufreq driver.
s//based on CPPC counters.
.. or more detailed: 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 8a482c434ea6..c4580a37a1b1 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
[..]
> +static void cppc_freq_invariance_policy_init(struct cpufreq_policy *policy,
> + struct cppc_cpudata *cpu_data)
> +{
> + struct cppc_freq_invariance *cppc_fi;
> + int i;
> +
> + if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
> + return;
> +
> + for_each_cpu(i, policy->cpus) {
> + cppc_fi = _cpu(cppc_freq_inv, i);
> + cppc_fi->cpu = i;
> + cppc_fi->cpu_data = cpu_data;
> + kthread_init_work(_fi->work, cppc_scale_freq_workfn);
> + init_irq_work(_fi->irq_work, cppc_irq_work);
> + }
> +}
> +
> +static void cppc_freq_invariance_exit(void)
> +{
> + struct cppc_freq_invariance *cppc_fi;
> + int i;
> +
> + if (cppc_cpufreq_driver.get == hisi_cppc_cpufreq_get_rate)
> + return;
> +
> + topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC,
> cpu_present_mask);
> +
> + for_each_possible_cpu(i) {
> + cppc_fi = _cpu(cppc_freq_inv, i);
> + irq_work_sync(_fi->irq_work);
> + }
> +
> + kthread_destroy_worker(kworker_fie);
> + kworker_fie = NULL;
> +}
> +
> +static void __init cppc_freq_invariance_init(void)
> +{
> + struct cppc_perf_fb_ctrs fb_ctrs = {0};
> + struct cppc_freq_invariance *cppc_fi;
> + 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"
> +
[PATCH V5 2/2] 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
freq_scale variable based on the counter updates since the last tick.
To allow platforms to disable frequency invariance support if they want,
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: Ionela Voinescu
Cc: linux-a...@vger.kernel.org
Signed-off-by: Viresh Kumar
---
drivers/cpufreq/Kconfig.arm| 9 ++
drivers/cpufreq/cppc_cpufreq.c | 244 +++--
include/linux/arch_topology.h | 1 +
kernel/sched/core.c| 1 +
4 files changed, 243 insertions(+), 12 deletions(-)
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index e65e0a43be64..a3e2d6dfea70 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -19,6 +19,15 @@ 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
+ default y
+ help
+ This enables frequency invariance support for CPPC cpufreq driver.
+
+ 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 8a482c434ea6..c4580a37a1b1 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
#include
#include
#include
#include
#include
#include
+#include
+#include
#include
#include
+#include
#include
@@ -57,6 +61,203 @@ 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 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 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, _ctrs)) {
+ pr_warn("%s: failed to read perf counters\n", __func__);
+ return;
+ }
+
+ cppc_fi->prev_perf_fb_ctrs =
