[RFC][PATCH v1 2/3] x86/sched: Introduce arch_rebuild_sched_domains()

Rafael J. Wysocki
2024-04-25T19:06:21Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add arch_rebuild_sched_domains() for rebuilding scheduling domains and
updating topology on x86 and make the ITMT code use it.

First of all, this reduces code duplication somewhat and eliminates
a need to use an extern variable, but it will also lay the ground for
future work related to CPU capacity scaling.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
arch/x86/include/asm/topology.h | 6 ++++--
arch/x86/kernel/itmt.c | 12 ++++--------
arch/x86/kernel/smpboot.c | 10 +++++++++-
3 files changed, 17 insertions(+), 11 deletions(-)

Index: linux-pm/arch/x86/include/asm/topology.h
===================================================================
--- linux-pm.orig/arch/x86/include/asm/topology.h
+++ linux-pm/arch/x86/include/asm/topology.h
@@ -235,8 +235,6 @@ struct pci_bus;
int x86_pci_root_bus_node(int bus);
void x86_pci_root_bus_resources(int bus, struct list_head *resources);

-extern bool x86_topology_update;
-
#ifdef CONFIG_SCHED_MC_PRIO
#include <asm/percpu.h>

@@ -284,9 +282,13 @@ static inline long arch_scale_freq_capac

extern void arch_set_max_freq_ratio(bool turbo_disabled);
extern void freq_invariance_set_perf_ratio(u64 ratio, bool turbo_disabled);
+
+void arch_rebuild_sched_domains(void);
#else
static inline void arch_set_max_freq_ratio(bool turbo_disabled) { }
static inline void freq_invariance_set_perf_ratio(u64 ratio, bool turbo_disabled) { }
+
+static inline void arch_rebuild_sched_domains(void) { }
#endif

extern void arch_scale_freq_tick(void);
Index: linux-pm/arch/x86/kernel/itmt.c
===================================================================
--- linux-pm.orig/arch/x86/kernel/itmt.c
+++ linux-pm/arch/x86/kernel/itmt.c
@@ -54,10 +54,8 @@ static int sched_itmt_update_handler(str
old_sysctl = sysctl_sched_itmt_enabled;
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

- if (!ret && write && old_sysctl != sysctl_sched_itmt_enabled) {
- x86_topology_update = true;
- rebuild_sched_domains();
- }
+ if (!ret && write && old_sysctl != sysctl_sched_itmt_enabled)
+ arch_rebuild_sched_domains();

mutex_unlock(&itmt_update_mutex);

@@ -114,8 +112,7 @@ int sched_set_itmt_support(void)

sysctl_sched_itmt_enabled = 1;

- x86_topology_update = true;
- rebuild_sched_domains();
+ arch_rebuild_sched_domains();

mutex_unlock(&itmt_update_mutex);

@@ -150,8 +147,7 @@ void sched_clear_itmt_support(void)
if (sysctl_sched_itmt_enabled) {
/* disable sched_itmt if we are no longer ITMT capable */
sysctl_sched_itmt_enabled = 0;
- x86_topology_update = true;
- rebuild_sched_domains();
+ arch_rebuild_sched_domains();
}

mutex_unlock(&itmt_update_mutex);
Index: linux-pm/arch/x86/kernel/smpboot.c
===================================================================
--- linux-pm.orig/arch/x86/kernel/smpboot.c
+++ linux-pm/arch/x86/kernel/smpboot.c
@@ -39,6 +39,7 @@

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+#include <linux/cpuset.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/export.h>
@@ -125,7 +126,7 @@ static DEFINE_PER_CPU_ALIGNED(struct mwa
int __read_mostly __max_smt_threads = 1;

/* Flag to indicate if a complete sched domain rebuild is required */
-bool x86_topology_update;
+static bool x86_topology_update;

int arch_update_cpu_topology(void)
{
@@ -135,6 +136,13 @@ int arch_update_cpu_topology(void)
return retval;
}

+#ifdef CONFIG_X86_64
+void arch_rebuild_sched_domains(void) {
+ x86_topology_update = true;
+ rebuild_sched_domains();
+}
+#endif
+
static unsigned int smpboot_warm_reset_vector_count;

static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)