2024-05-24 18:58:45

by Yury Norov

Subject: [PATCH] cpumask: introduce assign_cpu() macro

Now that assign_bit() is a thin macro wrapper around set_bit() and
clear_bit(), we can use it in cpumask API and drop duplicating
implementations of set_cpu_xxx() helpers with no additional overhead.

Bloat-o-meter reports almost 2k less of generated code for allyesconfig,
mostly in kernel/cpu.c:
add/remove: 2/4 grow/shrink: 3/4 up/down: 498/-2228 (-1730)

Signed-off-by: Yury Norov <[email protected]>
---
include/linux/cpumask.h | 40 ++++++----------------------------------
1 file changed, 6 insertions(+), 34 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 23686bed441d..06ce329741e2 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1083,44 +1083,16 @@ void init_cpu_present(const struct cpumask *src);
void init_cpu_possible(const struct cpumask *src);
void init_cpu_online(const struct cpumask *src);

-static inline void
-set_cpu_possible(unsigned int cpu, bool possible)
-{
- if (possible)
- cpumask_set_cpu(cpu, &__cpu_possible_mask);
- else
- cpumask_clear_cpu(cpu, &__cpu_possible_mask);
-}
+#define assign_cpu(cpu, mask, val) \
+ assign_bit(cpumask_check(cpu), cpumask_bits(mask), (val))

-static inline void
-set_cpu_present(unsigned int cpu, bool present)
-{
- if (present)
- cpumask_set_cpu(cpu, &__cpu_present_mask);
- else
- cpumask_clear_cpu(cpu, &__cpu_present_mask);
-}
+#define set_cpu_possible(cpu, possible) assign_cpu((cpu), &__cpu_possible_mask, (possible))
+#define set_cpu_present(cpu, present) assign_cpu((cpu), &__cpu_present_mask, (present))
+#define set_cpu_active(cpu, active) assign_cpu((cpu), &__cpu_active_mask, (active))
+#define set_cpu_dying(cpu, dying) assign_cpu((cpu), &__cpu_dying_mask, (dying))

void set_cpu_online(unsigned int cpu, bool online);

-static inline void
-set_cpu_active(unsigned int cpu, bool active)
-{
- if (active)
- cpumask_set_cpu(cpu, &__cpu_active_mask);
- else
- cpumask_clear_cpu(cpu, &__cpu_active_mask);
-}
-
-static inline void
-set_cpu_dying(unsigned int cpu, bool dying)
-{
- if (dying)
- cpumask_set_cpu(cpu, &__cpu_dying_mask);
- else
- cpumask_clear_cpu(cpu, &__cpu_dying_mask);
-}
-
/**
* to_cpumask - convert a NR_CPUS bitmap to a struct cpumask *
* @bitmap: the bitmap
--
2.40.1

2024-05-27 10:05:45

by Alexander Lobakin

Subject: Re: [PATCH] cpumask: introduce assign_cpu() macro

From: Yury Norov <[email protected]>
Date: Fri, 24 May 2024 11:58:28 -0700

> Now that assign_bit() is a thin macro wrapper around set_bit() and
> clear_bit(), we can use it in cpumask API and drop duplicating
> implementations of set_cpu_xxx() helpers with no additional overhead.
>
> Bloat-o-meter reports almost 2k less of generated code for allyesconfig,
> mostly in kernel/cpu.c:
> add/remove: 2/4 grow/shrink: 3/4 up/down: 498/-2228 (-1730)

Nice save!

>
> Signed-off-by: Yury Norov <[email protected]>

Reviewed-by: Alexander Lobakin <[email protected]>

Thanks,
Olek