From: Yury Norov <yury.norov@gmail.com>
To: "Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Alexander Lobakin" <alobakin@pm.me>,
"Huacai Chen" <chenhuacai@kernel.org>,
"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
"Mao Bibo" <maobibo@loongson.cn>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"WANG Xuerui" <kernel@xen0n.name>,
linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>
Subject: [PATCH] mips: micro-optimize calculate_cpu_foreign_map()
Date: Tue, 21 Jun 2022 07:47:29 -0700 [thread overview]
Message-ID: <20220621144729.533026-1-yury.norov@gmail.com> (raw)
The inner loop in calculate_cpu_foreign_map() walks the whole
cpumask to check if we have siblings for a given cpu.
We can just break after a 1st match and avoid useless traversing
the rest of mask.
Loongarch has an identical function, so fix it here as well.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
It looks like loongarch copied quite a lot from arch/mips/kernel/smp.c.
For loongarch folks: Guys, can you consider moving shared code into a
shared file(s)?
arch/loongarch/kernel/smp.c | 7 +++----
arch/mips/kernel/smp.c | 7 +++----
2 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
index b8c53b755a25..c1c91df3c8ac 100644
--- a/arch/loongarch/kernel/smp.c
+++ b/arch/loongarch/kernel/smp.c
@@ -463,17 +463,16 @@ static inline void set_cpu_core_map(int cpu)
*/
void calculate_cpu_foreign_map(void)
{
- int i, k, core_present;
+ int i, k;
cpumask_t temp_foreign_map;
/* Re-calculate the mask */
cpumask_clear(&temp_foreign_map);
for_each_online_cpu(i) {
- core_present = 0;
for_each_cpu(k, &temp_foreign_map)
if (cpus_are_siblings(i, k))
- core_present = 1;
- if (!core_present)
+ break;
+ if (k >= nr_cpu_ids)
cpumask_set_cpu(i, &temp_foreign_map);
}
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 1d93b85271ba..a2ce641f5f18 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -115,17 +115,16 @@ static inline void set_cpu_core_map(int cpu)
*/
void calculate_cpu_foreign_map(void)
{
- int i, k, core_present;
+ int i, k;
cpumask_t temp_foreign_map;
/* Re-calculate the mask */
cpumask_clear(&temp_foreign_map);
for_each_online_cpu(i) {
- core_present = 0;
for_each_cpu(k, &temp_foreign_map)
if (cpus_are_siblings(i, k))
- core_present = 1;
- if (!core_present)
+ break;
+ if (k >= nr_cpu_ids)
cpumask_set_cpu(i, &temp_foreign_map);
}
--
2.32.0
next reply other threads:[~2022-06-21 14:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-21 14:47 Yury Norov [this message]
2022-07-01 2:59 ` [PATCH] mips: micro-optimize calculate_cpu_foreign_map() Yury Norov
2022-07-05 10:40 ` Thomas Bogendoerfer
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