[PATCH v4 1/4] smpboot: introduce SDTL() helper to tidy sched topology setup

[PATCH v4 1/4] smpboot: introduce SDTL() helper to tidy sched topology setup

[Li Chen]

From: Li Chen <chenl311@chinatelecom.cn>

Define a small SDTL(maskfn, flagsfn, name) macro and use it to build the
sched_domain_topology_level. Purely a cleanup; behaviour is unchanged.

Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/powerpc/kernel/smp.c      | 34 +++++++++++++---------------------
 arch/s390/kernel/topology.c    | 10 +++++-----
 arch/x86/kernel/smpboot.c      | 21 ++++++---------------
 include/linux/sched/topology.h |  6 +++---
 kernel/sched/topology.c        | 16 ++++++----------
 5 files changed, 33 insertions(+), 54 deletions(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5ac7084eebc0b..b05995e272134 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1700,28 +1700,20 @@ static void __init build_sched_topology(void)
 #ifdef CONFIG_SCHED_SMT
 	if (has_big_cores) {
 		pr_info("Big cores detected but using small core scheduling\n");
-		powerpc_topology[i++] = (struct sched_domain_topology_level){
-			smallcore_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT)
-		};
-	} else {
-		powerpc_topology[i++] = (struct sched_domain_topology_level){
-			cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT)
-		};
-	}
+		powerpc_topology[i++] =
+			SDTL(smallcore_smt_mask, powerpc_smt_flags, SMT);
+	} else
+		powerpc_topology[i++] = SDTL(cpu_smt_mask, powerpc_smt_flags, SMT);
 #endif
-	if (shared_caches) {
-		powerpc_topology[i++] = (struct sched_domain_topology_level){
-			shared_cache_mask, powerpc_shared_cache_flags, SD_INIT_NAME(CACHE)
-		};
-	}
-	if (has_coregroup_support()) {
-		powerpc_topology[i++] = (struct sched_domain_topology_level){
-			cpu_mc_mask, powerpc_shared_proc_flags, SD_INIT_NAME(MC)
-		};
-	}
-	powerpc_topology[i++] = (struct sched_domain_topology_level){
-		cpu_cpu_mask, powerpc_shared_proc_flags, SD_INIT_NAME(PKG)
-	};
+	if (shared_caches)
+		powerpc_topology[i++] =
+			SDTL(shared_cache_mask, powerpc_shared_cache_flags, CACHE);
+
+	if (has_coregroup_support())
+		powerpc_topology[i++] =
+			SDTL(cpu_mc_mask, powerpc_shared_proc_flags, MC);
+
+	powerpc_topology[i++] = SDTL(cpu_cpu_mask, powerpc_shared_proc_flags, PKG);
 
 	/* There must be one trailing NULL entry left.  */
 	BUG_ON(i >= ARRAY_SIZE(powerpc_topology) - 1);
diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index 3df048e190b11..ccf5dcc56f86d 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -531,11 +531,11 @@ static const struct cpumask *cpu_drawer_mask(int cpu)
 }
 
 static struct sched_domain_topology_level s390_topology[] = {
-	{ cpu_thread_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
-	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
-	{ cpu_book_mask, SD_INIT_NAME(BOOK) },
-	{ cpu_drawer_mask, SD_INIT_NAME(DRAWER) },
-	{ cpu_cpu_mask, SD_INIT_NAME(PKG) },
+	SDTL(cpu_thread_mask, cpu_smt_flags, SMT),
+	SDTL(cpu_coregroup_mask, cpu_core_flags, MC),
+	SDTL(cpu_book_mask, NULL, BOOK),
+	SDTL(cpu_drawer_mask, NULL, DRAWER),
+	SDTL(cpu_cpu_mask, NULL, PKG),
 	{ NULL, },
 };
 
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 58ede3fa6a75b..55f09946c791b 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -485,35 +485,26 @@ static void __init build_sched_topology(void)
 	int i = 0;
 
 #ifdef CONFIG_SCHED_SMT
-	x86_topology[i++] = (struct sched_domain_topology_level){
-		cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT)
-	};
+	x86_topology[i++] = SDTL(cpu_smt_mask, cpu_smt_flags, SMT);
 #endif
 #ifdef CONFIG_SCHED_CLUSTER
-	x86_topology[i++] = (struct sched_domain_topology_level){
-		cpu_clustergroup_mask, x86_cluster_flags, SD_INIT_NAME(CLS)
-	};
+	x86_topology[i++] = SDTL(cpu_clustergroup_mask, x86_cluster_flags, CLS);
 #endif
 #ifdef CONFIG_SCHED_MC
-	x86_topology[i++] = (struct sched_domain_topology_level){
-		cpu_coregroup_mask, x86_core_flags, SD_INIT_NAME(MC)
-	};
+	x86_topology[i++] = SDTL(cpu_coregroup_mask, x86_core_flags, MC);
 #endif
 	/*
 	 * When there is NUMA topology inside the package skip the PKG domain
 	 * since the NUMA domains will auto-magically create the right spanning
 	 * domains based on the SLIT.
 	 */
-	if (!x86_has_numa_in_package) {
-		x86_topology[i++] = (struct sched_domain_topology_level){
-			cpu_cpu_mask, x86_sched_itmt_flags, SD_INIT_NAME(PKG)
-		};
-	}
+	if (!x86_has_numa_in_package)
+		x86_topology[i++] = SDTL(cpu_cpu_mask, x86_sched_itmt_flags, PKG);
 
 	/*
 	 * There must be one trailing NULL entry left.
 	 */
-	BUG_ON(i >= ARRAY_SIZE(x86_topology)-1);
+	BUG_ON(i >= ARRAY_SIZE(x86_topology) - 1);
 
 	set_sched_topology(x86_topology);
 }
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index 198bb5cc1774b..0b53e372c445c 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -197,9 +197,9 @@ struct sched_domain_topology_level {
 extern void __init set_sched_topology(struct sched_domain_topology_level *tl);
 extern void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio);
 
-
-# define SD_INIT_NAME(type)		.name = #type
-
+#define SDTL(maskfn, flagsfn, dname) \
+	((struct sched_domain_topology_level) \
+	    { .mask = maskfn, .sd_flags = flagsfn, .name = #dname, .numa_level = 0 })
 #else /* CONFIG_SMP */
 
 struct sched_domain_attr;
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index b958fe48e0205..e6ec65ae4b75d 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1739,17 +1739,17 @@ sd_init(struct sched_domain_topology_level *tl,
  */
 static struct sched_domain_topology_level default_topology[] = {
 #ifdef CONFIG_SCHED_SMT
-	{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
+	SDTL(cpu_smt_mask, cpu_smt_flags, SMT),
 #endif
 
 #ifdef CONFIG_SCHED_CLUSTER
-	{ cpu_clustergroup_mask, cpu_cluster_flags, SD_INIT_NAME(CLS) },
+	SDTL(cpu_clustergroup_mask, cpu_cluster_flags, CLS),
 #endif
 
 #ifdef CONFIG_SCHED_MC
-	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
+	SDTL(cpu_coregroup_mask, cpu_core_flags, MC),
 #endif
-	{ cpu_cpu_mask, SD_INIT_NAME(PKG) },
+	SDTL(cpu_cpu_mask, NULL, PKG),
 	{ NULL, },
 };
 
@@ -2010,11 +2010,7 @@ void sched_init_numa(int offline_node)
 	/*
 	 * Add the NUMA identity distance, aka single NODE.
 	 */
-	tl[i++] = (struct sched_domain_topology_level){
-		.mask = sd_numa_mask,
-		.numa_level = 0,
-		SD_INIT_NAME(NODE)
-	};
+	tl[i++] = SDTL(sd_numa_mask, NULL, NODE);
 
 	/*
 	 * .. and append 'j' levels of NUMA goodness.
@@ -2025,7 +2021,7 @@ void sched_init_numa(int offline_node)
 			.sd_flags = cpu_numa_flags,
 			.flags = SDTL_OVERLAP,
 			.numa_level = j,
-			SD_INIT_NAME(NUMA)
+			.name = "NUMA",
 		};
 	}
 
-- 
2.49.0

Re: [PATCH v4 1/4] smpboot: introduce SDTL() helper to tidy sched topology setup

[K Prateek Nayak]

Hello Li,

Apart from few comments inline below, feel free to include:

Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>

for the entire series.

On 7/6/2025 8:36 AM, Li Chen wrote:
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 198bb5cc1774b..0b53e372c445c 100644
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -197,9 +197,9 @@ struct sched_domain_topology_level {
>  extern void __init set_sched_topology(struct sched_domain_topology_level *tl);
>  extern void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio);
>  
> -
> -# define SD_INIT_NAME(type)		.name = #type
> -
> +#define SDTL(maskfn, flagsfn, dname) \
> +	((struct sched_domain_topology_level) \
> +	    { .mask = maskfn, .sd_flags = flagsfn, .name = #dname, .numa_level = 0 })

I prefer the following alignment:

#define SDTL(maskfn, flagsfn, dname) ((struct sched_domain_topology_level) \
	{ .mask = maskfn, .sd_flags = flagsfn, .name = #dname })

instead of having 3 lines. "numa_level" is 0 by default so I don't think
we need to explicitly specify it again.

Also perhaps the macro can be named "SDTL_INIT()" to keep consistent
with the naming convention.

>  #else /* CONFIG_SMP */

A bunch of the CONFIG_SMP related ifdeffry is being removed for the
next cycle. You can perhaps rebase the series on top of the tip tree
(git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git)

>  
>  struct sched_domain_attr;

[..snip..]

> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index b958fe48e0205..e6ec65ae4b75d 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2025,7 +2021,7 @@ void sched_init_numa(int offline_node)
>  			.sd_flags = cpu_numa_flags,
>  			.flags = SDTL_OVERLAP,
>  			.numa_level = j,
> -			SD_INIT_NAME(NUMA)
> +			.name = "NUMA",

This can use SDTL() macro too. Just explicitly set "tl[i].numa_level" to
"j" after.

>  		};
>  	}
>  

-- 
Thanks and Regards,
Prateek

Re: [PATCH v4 1/4] smpboot: introduce SDTL() helper to tidy sched topology setup

[Li Chen]

Hi K,

Thanks for your reviews and test! I have addressed all issues in v5:
https://www.spinics.net/lists/kernel/msg5761848.html

 ---- On Mon, 07 Jul 2025 13:33:53 +0800  K Prateek Nayak <kprateek.nayak@amd.com> wrote --- 
 > Hello Li,
 > 
 > Apart from few comments inline below, feel free to include:
 > 
 > Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
 > 
 > for the entire series.
 > 
 > On 7/6/2025 8:36 AM, Li Chen wrote:
 > > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
 > > index 198bb5cc1774b..0b53e372c445c 100644
 > > --- a/include/linux/sched/topology.h
 > > +++ b/include/linux/sched/topology.h
 > > @@ -197,9 +197,9 @@ struct sched_domain_topology_level {
 > >  extern void __init set_sched_topology(struct sched_domain_topology_level *tl);
 > >  extern void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio);
 > >  
 > > -
 > > -# define SD_INIT_NAME(type)        .name = #type
 > > -
 > > +#define SDTL(maskfn, flagsfn, dname) \
 > > +    ((struct sched_domain_topology_level) \
 > > +        { .mask = maskfn, .sd_flags = flagsfn, .name = #dname, .numa_level = 0 })
 > 
 > I prefer the following alignment:
 > 
 > #define SDTL(maskfn, flagsfn, dname) ((struct sched_domain_topology_level) \
 >     { .mask = maskfn, .sd_flags = flagsfn, .name = #dname })
 > 
 > instead of having 3 lines. "numa_level" is 0 by default so I don't think
 > we need to explicitly specify it again.
 > 
 > Also perhaps the macro can be named "SDTL_INIT()" to keep consistent
 > with the naming convention.
 > 
 > >  #else /* CONFIG_SMP */
 > 
 > A bunch of the CONFIG_SMP related ifdeffry is being removed for the
 > next cycle. You can perhaps rebase the series on top of the tip tree
 > (git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git)
 > 
 > >  
 > >  struct sched_domain_attr;
 > 
 > [..snip..]
 > 
 > > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
 > > index b958fe48e0205..e6ec65ae4b75d 100644
 > > --- a/kernel/sched/topology.c
 > > +++ b/kernel/sched/topology.c
 > > @@ -2025,7 +2021,7 @@ void sched_init_numa(int offline_node)
 > >              .sd_flags = cpu_numa_flags,
 > >              .flags = SDTL_OVERLAP,
 > >              .numa_level = j,
 > > -            SD_INIT_NAME(NUMA)
 > > +            .name = "NUMA",
 > 
 > This can use SDTL() macro too. Just explicitly set "tl[i].numa_level" to
 > "j" after.
 > 
 > >          };
 > >      }
 > >  
 > 
 > -- 
 > Thanks and Regards,
 > Prateek
 > 
 > 
Regards,

Li​