* [PATCH] mips: micro-optimize calculate_cpu_foreign_map()
@ 2022-06-21 14:47 Yury Norov
2022-07-01 2:59 ` Yury Norov
0 siblings, 1 reply; 3+ messages in thread
From: Yury Norov @ 2022-06-21 14:47 UTC (permalink / raw)
To: Thomas Bogendoerfer, Alexander Lobakin, Huacai Chen, Jiaxun Yang,
Mao Bibo, Philippe Mathieu-Daudé, WANG Xuerui, linux-kernel,
linux-mips
Cc: Yury Norov
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mips: micro-optimize calculate_cpu_foreign_map()
2022-06-21 14:47 [PATCH] mips: micro-optimize calculate_cpu_foreign_map() Yury Norov
@ 2022-07-01 2:59 ` Yury Norov
2022-07-05 10:40 ` Thomas Bogendoerfer
0 siblings, 1 reply; 3+ messages in thread
From: Yury Norov @ 2022-07-01 2:59 UTC (permalink / raw)
To: Thomas Bogendoerfer, Alexander Lobakin, Huacai Chen, Jiaxun Yang,
Mao Bibo, Philippe Mathieu-Daudé, WANG Xuerui, linux-kernel,
linux-mips
On Tue, Jun 21, 2022 at 07:47:29AM -0700, Yury Norov wrote:
> 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>
Ping?
> ---
>
> 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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mips: micro-optimize calculate_cpu_foreign_map()
2022-07-01 2:59 ` Yury Norov
@ 2022-07-05 10:40 ` Thomas Bogendoerfer
0 siblings, 0 replies; 3+ messages in thread
From: Thomas Bogendoerfer @ 2022-07-05 10:40 UTC (permalink / raw)
To: Yury Norov
Cc: Alexander Lobakin, Huacai Chen, Jiaxun Yang, Mao Bibo,
Philippe Mathieu-Daudé, WANG Xuerui, linux-kernel,
linux-mips
On Thu, Jun 30, 2022 at 07:59:04PM -0700, Yury Norov wrote:
> On Tue, Jun 21, 2022 at 07:47:29AM -0700, Yury Norov wrote:
> > 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>
>
> Ping?
as this is touching two different archs, it would have been easier
to send this in two different patches.
Huacai, should I take the patch ?
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-06-21 14:47 [PATCH] mips: micro-optimize calculate_cpu_foreign_map() Yury Norov
2022-07-01 2:59 ` Yury Norov
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