linux-kernel - Re: [RFC][PATCH v1 2/3] x86/sched: Introduce arch_rebuild_sched

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Date: Thu, 25 Apr 2024 21:14:08 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: x86 Maintainers <x86@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>,
 Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
 Ricardo Neri <ricardo.neri@...el.com>, Tim Chen <tim.c.chen@...el.com>
Subject:
 Re: [RFC][PATCH v1 2/3] x86/sched: Introduce arch_rebuild_sched_domains()

On Thursday, April 25, 2024 9:04:48 PM CEST Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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@...el.com>

This obviously is a duplicate of patch [1/3], sorry about this.  My bad.

I'll send the proper patch [2/3] in a reply to this message.

> ---
>  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)
>