2024-02-13 21:27:54

by Thomas Gleixner

Subject: [patch 23/30] x86/cpu/topology: Simplify cpu_mark_primary_thread()

From: Thomas Gleixner <[email protected]>

No point in creating a mask via fls(). smp_num_siblings is guaranteed to be
a power of 2. So just using (smp_num_siblings - 1) has the same effect.

Signed-off-by: Thomas Gleixner <[email protected]>




---
arch/x86/kernel/cpu/topology.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
---

--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -76,10 +76,7 @@ bool arch_match_cpu_phys_id(int cpu, u64
#ifdef CONFIG_SMP
static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
{
- /* Isolate the SMT bit(s) in the APICID and check for 0 */
- u32 mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
-
- if (smp_num_siblings == 1 || !(apicid & mask))
+ if (!(apicid & (smp_num_siblings - 1)))
cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
}
#else

2024-02-16 15:17:57

by tip-bot2 for Alexey Makhalov

Subject: [tip: x86/apic] x86/cpu/topology: Simplify cpu_mark_primary_thread()

The following commit has been merged into the x86/apic branch of tip:

Commit-ID: 5e40fb2d4a4c7503cab4f923b7d985dbcf583581
Gitweb: https://git.kernel.org/tip/5e40fb2d4a4c7503cab4f923b7d985dbcf583581
Author: Thomas Gleixner <[email protected]>
AuthorDate: Tue, 13 Feb 2024 22:06:06 +01:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Thu, 15 Feb 2024 22:07:44 +01:00

x86/cpu/topology: Simplify cpu_mark_primary_thread()

No point in creating a mask via fls(). smp_num_siblings is guaranteed to be
a power of 2. So just using (smp_num_siblings - 1) has the same effect.

Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Tested-by: Sohil Mehta <[email protected]>
Link: https://lore.kernel.org/r/[email protected]





---
arch/x86/kernel/cpu/topology.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index f3397e2..aea408d 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -76,10 +76,7 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
#ifdef CONFIG_SMP
static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
{
- /* Isolate the SMT bit(s) in the APICID and check for 0 */
- u32 mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
-
- if (smp_num_siblings == 1 || !(apicid & mask))
+ if (!(apicid & (smp_num_siblings - 1)))
cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
}
#else