[PATCH 1/2] x86, sched: Calculate frequency invariance for AMD systems
Kai-Heng Feng
kai.heng.feng at canonical.com
Tue Jun 22 17:16:22 UTC 2021
From: Nathan Fontenot <nathan.fontenot at amd.com>
BugLink: https://bugs.launchpad.net/bugs/1928482
This is the first pass in creating the ability to calculate the
frequency invariance on AMD systems. This approach uses the CPPC
highest performance and nominal performance values that range from
0 - 255 instead of a high and base frquency. This is because we do
not have the ability on AMD to get a highest frequency value.
On AMD systems the highest performance and nominal performance
vaues do correspond to the highest and base frequencies for the system
so using them should produce an appropriate ratio but some tweaking
is likely necessary.
Due to CPPC being initialized later in boot than when the frequency
invariant calculation is currently made, I had to create a callback
from the CPPC init code to do the calculation after we have CPPC
data.
Special thanks to "kernel test robot <lkp at intel.com>" for reporting that
compilation of drivers/acpi/cppc_acpi.c is conditional to
CONFIG_ACPI_CPPC_LIB, not just CONFIG_ACPI.
[ ggherdovich at suse.cz: made safe under CPU hotplug, edited changelog. ]
Signed-off-by: Nathan Fontenot <nathan.fontenot at amd.com>
Signed-off-by: Giovanni Gherdovich <ggherdovich at suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Link: https://lkml.kernel.org/r/20201112182614.10700-2-ggherdovich@suse.cz
(cherry picked from commit 41ea667227bad5c247d76e6605054e96e4d95f51)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
arch/x86/include/asm/topology.h | 5 +++
arch/x86/kernel/smpboot.c | 76 ++++++++++++++++++++++++++++++---
drivers/acpi/cppc_acpi.c | 7 +++
3 files changed, 83 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 1f6caceccbb0..9239399e5491 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -218,4 +218,9 @@ static inline void arch_set_max_freq_ratio(bool turbo_disabled)
}
#endif
+#ifdef CONFIG_ACPI_CPPC_LIB
+void init_freq_invariance_cppc(void);
+#define init_freq_invariance_cppc init_freq_invariance_cppc
+#endif
+
#endif /* _ASM_X86_TOPOLOGY_H */
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 582387fc939f..dc7534d01f72 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -82,6 +82,10 @@
#include <asm/hw_irq.h>
#include <asm/stackprotector.h>
+#ifdef CONFIG_ACPI_CPPC_LIB
+#include <acpi/cppc_acpi.h>
+#endif
+
/* representing HT siblings of each logical CPU */
DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
@@ -148,7 +152,7 @@ static inline void smpboot_restore_warm_reset_vector(void)
*((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0;
}
-static void init_freq_invariance(bool secondary);
+static void init_freq_invariance(bool secondary, bool cppc_ready);
/*
* Report back to the Boot Processor during boot time or to the caller processor
@@ -186,7 +190,7 @@ static void smp_callin(void)
*/
set_cpu_sibling_map(raw_smp_processor_id());
- init_freq_invariance(true);
+ init_freq_invariance(true, false);
/*
* Get our bogomips.
@@ -1342,7 +1346,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
set_sched_topology(x86_topology);
set_cpu_sibling_map(0);
- init_freq_invariance(false);
+ init_freq_invariance(false, false);
smp_sanity_check();
switch (apic_intr_mode) {
@@ -2028,6 +2032,46 @@ static bool intel_set_max_freq_ratio(void)
return true;
}
+#ifdef CONFIG_ACPI_CPPC_LIB
+static bool amd_set_max_freq_ratio(void)
+{
+ struct cppc_perf_caps perf_caps;
+ u64 highest_perf, nominal_perf;
+ u64 perf_ratio;
+ int rc;
+
+ rc = cppc_get_perf_caps(0, &perf_caps);
+ if (rc) {
+ pr_debug("Could not retrieve perf counters (%d)\n", rc);
+ return false;
+ }
+
+ highest_perf = perf_caps.highest_perf;
+ nominal_perf = perf_caps.nominal_perf;
+
+ if (!highest_perf || !nominal_perf) {
+ pr_debug("Could not retrieve highest or nominal performance\n");
+ return false;
+ }
+
+ perf_ratio = div_u64(highest_perf * SCHED_CAPACITY_SCALE, nominal_perf);
+ if (!perf_ratio) {
+ pr_debug("Non-zero highest/nominal perf values led to a 0 ratio\n");
+ return false;
+ }
+
+ arch_turbo_freq_ratio = perf_ratio;
+ arch_set_max_freq_ratio(false);
+
+ return true;
+}
+#else
+static bool amd_set_max_freq_ratio(void)
+{
+ return false;
+}
+#endif
+
static void init_counter_refs(void)
{
u64 aperf, mperf;
@@ -2039,7 +2083,7 @@ static void init_counter_refs(void)
this_cpu_write(arch_prev_mperf, mperf);
}
-static void init_freq_invariance(bool secondary)
+static void init_freq_invariance(bool secondary, bool cppc_ready)
{
bool ret = false;
@@ -2055,6 +2099,12 @@ static void init_freq_invariance(bool secondary)
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
ret = intel_set_max_freq_ratio();
+ else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (!cppc_ready) {
+ return;
+ }
+ ret = amd_set_max_freq_ratio();
+ }
if (ret) {
init_counter_refs();
@@ -2064,6 +2114,22 @@ static void init_freq_invariance(bool secondary)
}
}
+#ifdef CONFIG_ACPI_CPPC_LIB
+static DEFINE_MUTEX(freq_invariance_lock);
+
+void init_freq_invariance_cppc(void)
+{
+ static bool secondary;
+
+ mutex_lock(&freq_invariance_lock);
+
+ init_freq_invariance(secondary, true);
+ secondary = true;
+
+ mutex_unlock(&freq_invariance_lock);
+}
+#endif
+
static void disable_freq_invariance_workfn(struct work_struct *work)
{
static_branch_disable(&arch_scale_freq_key);
@@ -2113,7 +2179,7 @@ void arch_scale_freq_tick(void)
schedule_work(&disable_freq_invariance_work);
}
#else
-static inline void init_freq_invariance(bool secondary)
+static inline void init_freq_invariance(bool secondary, bool cppc_ready)
{
}
#endif /* CONFIG_X86_64 */
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 0a2da06e9d8b..adae06e0bbf1 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -39,6 +39,7 @@
#include <linux/ktime.h>
#include <linux/rwsem.h>
#include <linux/wait.h>
+#include <linux/topology.h>
#include <acpi/cppc_acpi.h>
@@ -680,6 +681,10 @@ static bool is_cppc_supported(int revision, int num_ent)
* }
*/
+#ifndef init_freq_invariance_cppc
+static inline void init_freq_invariance_cppc(void) { }
+#endif
+
/**
* acpi_cppc_processor_probe - Search for per CPU _CPC objects.
* @pr: Ptr to acpi_processor containing this CPU's logical ID.
@@ -842,6 +847,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
goto out_free;
}
+ init_freq_invariance_cppc();
+
kfree(output.pointer);
return 0;
--
2.31.1
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