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Message-ID: <20220328112344.GA557306@linux.vnet.ibm.com>
Date: Mon, 28 Mar 2022 16:53:44 +0530
From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To: Qing Wang <wangqing@...o.com>
Cc: Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched: topology: add input parameter for
sched_domain_flags_f()
* Qing Wang <wangqing@...o.com> [2022-03-28 02:53:37]:
> From: Wang Qing <wangqing@...o.com>
>
> sched_domain_flags_f() are statically set now, but actually, we can get a
> lot of necessary information based on the cpu_map. e.g. we can know whether
> its cache is shared.
>
> Allows custom extension without affecting current.
>
can you elaborate on how passing a cpumask pointer will help us to know if
cache is shared or not? With this patch, we are just passing the cpumask,
but dont seem to be using it in any of the cases.
or did I miss anything?
> Signed-off-by: Wang Qing <wangqing@...o.com>
> ---
> arch/powerpc/kernel/smp.c | 4 ++--
> arch/x86/kernel/smpboot.c | 8 ++++----
> include/linux/sched/topology.h | 10 +++++-----
> kernel/sched/topology.c | 2 +-
> 4 files changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index de0f6f0..e503d23
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -1000,7 +1000,7 @@ static bool shared_caches;
>
> #ifdef CONFIG_SCHED_SMT
> /* cpumask of CPUs with asymmetric SMT dependency */
> -static int powerpc_smt_flags(void)
> +static int powerpc_smt_flags(const struct cpumask *cpu_map)
> {
> int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
>
> @@ -1018,7 +1018,7 @@ static int powerpc_smt_flags(void)
> * since the migrated task remains cache hot. We want to take advantage of this
> * at the scheduler level so an extra topology level is required.
> */
> -static int powerpc_shared_cache_flags(void)
> +static int powerpc_shared_cache_flags(const struct cpumask *cpu_map)
> {
> return SD_SHARE_PKG_RESOURCES;
> }
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 2ef1477..c005a8e
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -535,25 +535,25 @@ static bool match_llc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>
>
> #if defined(CONFIG_SCHED_SMT) || defined(CONFIG_SCHED_CLUSTER) || defined(CONFIG_SCHED_MC)
> -static inline int x86_sched_itmt_flags(void)
> +static inline int x86_sched_itmt_flags(const struct cpumask *cpu_map)
> {
> return sysctl_sched_itmt_enabled ? SD_ASYM_PACKING : 0;
> }
>
> #ifdef CONFIG_SCHED_MC
> -static int x86_core_flags(void)
> +static int x86_core_flags(const struct cpumask *cpu_map)
> {
> return cpu_core_flags() | x86_sched_itmt_flags();
> }
> #endif
> #ifdef CONFIG_SCHED_SMT
> -static int x86_smt_flags(void)
> +static int x86_smt_flags(const struct cpumask *cpu_map)
> {
> return cpu_smt_flags() | x86_sched_itmt_flags();
> }
> #endif
> #ifdef CONFIG_SCHED_CLUSTER
> -static int x86_cluster_flags(void)
> +static int x86_cluster_flags(const struct cpumask *cpu_map)
> {
> return cpu_cluster_flags() | x86_sched_itmt_flags();
> }
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 56cffe4..6aa985a
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -36,28 +36,28 @@ extern const struct sd_flag_debug sd_flag_debug[];
> #endif
>
> #ifdef CONFIG_SCHED_SMT
> -static inline int cpu_smt_flags(void)
> +static inline int cpu_smt_flags(const struct cpumask *cpu_map)
> {
> return SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
> }
> #endif
>
> #ifdef CONFIG_SCHED_CLUSTER
> -static inline int cpu_cluster_flags(void)
> +static inline int cpu_cluster_flags(const struct cpumask *cpu_map)
> {
> return SD_SHARE_PKG_RESOURCES;
> }
> #endif
>
> #ifdef CONFIG_SCHED_MC
> -static inline int cpu_core_flags(void)
> +static inline int cpu_core_flags(const struct cpumask *cpu_map)
> {
> return SD_SHARE_PKG_RESOURCES;
> }
> #endif
>
> #ifdef CONFIG_NUMA
> -static inline int cpu_numa_flags(void)
> +static inline int cpu_numa_flags(const struct cpumask *cpu_map)
> {
> return SD_NUMA;
> }
> @@ -180,7 +180,7 @@ void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms);
> bool cpus_share_cache(int this_cpu, int that_cpu);
>
> typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
> -typedef int (*sched_domain_flags_f)(void);
> +typedef int (*sched_domain_flags_f)(const struct cpumask *cpu_map);
>
> #define SDTL_OVERLAP 0x01
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 05b6c2a..34dfec4
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -1556,7 +1556,7 @@ sd_init(struct sched_domain_topology_level *tl,
> sd_weight = cpumask_weight(tl->mask(cpu));
>
> if (tl->sd_flags)
> - sd_flags = (*tl->sd_flags)();
> + sd_flags = (*tl->sd_flags)(tl->mask(cpu));
> if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
> "wrong sd_flags in topology description\n"))
> sd_flags &= TOPOLOGY_SD_FLAGS;
> --
> 2.7.4
>
>
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