From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, kprateek.nayak@amd.com,
iii@linux.ibm.com, tglx@kernel.org, gregkh@linuxfoundation.org,
pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com,
huschle@linux.ibm.com, rostedt@goodmis.org,
dietmar.eggemann@arm.com, mgorman@suse.de, bsegall@google.com,
maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com,
chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org,
arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com,
tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org,
rafael@kernel.org
Subject: Re: [PATCH v4 04/20] cpumask: Introduce cpu_preferred_mask
Date: Thu, 18 Jun 2026 13:57:10 +0530 [thread overview]
Message-ID: <3e07e244-b3be-44a1-a541-b9dafd0ec314@linux.ibm.com> (raw)
In-Reply-To: <0f90bdcc-857f-4ffa-91a5-60965fae3d8f@linux.ibm.com>
On 6/18/26 9:23 AM, Shrikanth Hegde wrote:
> Hi Yury.
>
>>> +void set_cpu_preferred(unsigned int cpu, bool preferred)
>>> +{
>>> + if (!IS_ENABLED(CONFIG_PREFERRED_CPU))
>>> + return;
>>> +
>>> + assign_cpu((cpu), &__cpu_preferred_mask, (preferred));
>>> +}
>>
>> set_cpu_xxx() is a macro on purpose - it improves code generation
>> quite a lot. See 5c563ee90a22d. Can you keep set_cpu_preferred aligned
>> with the other set_cpu(), i.e. make it a macro?
>>
>
> Ok. only reason was to avoid ifdeffery there.
>
> you mean below?
>
> #ifdef CONFIG_PREFERRED_CPU
> #else
> #endif
>
Ok. I misread your comment. I believe you meant to do like below.
preferred mask is always defined, either same as active or allocated.
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 30ea64cc1656..5a643d608ea6 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1169,10 +1169,10 @@ void init_cpu_possible(const struct cpumask *src);
#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))
+#define set_cpu_preferred(cpu, preferred) assign_cpu((cpu), &__cpu_preferred_mask, (preferred))
void set_cpu_online(unsigned int cpu, bool online);
void set_cpu_possible(unsigned int cpu, bool possible);
-void set_cpu_preferred(unsigned int cpu, bool preferred);
/**
* to_cpumask - convert a NR_CPUS bitmap to a struct cpumask *
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c196ba5d8b2a..d623a9c5554a 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3159,14 +3159,6 @@ void set_cpu_possible(unsigned int cpu, bool possible)
}
}
-void set_cpu_preferred(unsigned int cpu, bool preferred)
-{
- if (!IS_ENABLED(CONFIG_PREFERRED_CPU))
- return;
-
- assign_cpu((cpu), &__cpu_preferred_mask, (preferred));
-}
-
/*
* Activate the first processor.
*/
next prev parent reply other threads:[~2026-06-18 8:27 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-17 17:41 [PATCH v4 00/20] sched: Introduce cpu_preferred_mask and steal-driven vCPU backoff Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 01/20] sched/debug: Remove unused schedstats Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 02/20] sched/docs: Document cpu_preferred_mask and Preferred CPU concept Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 03/20] kconfig: Provide PREFERRED_CPU option Shrikanth Hegde
2026-06-18 0:51 ` Yury Norov
2026-06-18 3:44 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 04/20] cpumask: Introduce cpu_preferred_mask Shrikanth Hegde
2026-06-18 1:29 ` Yury Norov
2026-06-18 3:53 ` Shrikanth Hegde
2026-06-18 8:27 ` Shrikanth Hegde [this message]
2026-06-17 17:41 ` [PATCH v4 05/20] sysfs: Add preferred CPU file Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 06/20] sched/core: allow only preferred CPUs in is_cpu_allowed Shrikanth Hegde
2026-06-18 3:32 ` Yury Norov
2026-06-18 4:17 ` Shrikanth Hegde
2026-06-18 4:49 ` Yury Norov
2026-06-18 5:14 ` Shrikanth Hegde
2026-06-18 3:49 ` K Prateek Nayak
2026-06-18 4:22 ` Shrikanth Hegde
2026-06-18 14:12 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 07/20] sched/fair: Select preferred CPU at wakeup when possible Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 08/20] sched/fair: load balance only among preferred CPUs Shrikanth Hegde
2026-06-18 3:03 ` K Prateek Nayak
2026-06-18 3:54 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 09/20] sched/core: Keep tick on non-preferred CPUs until tasks are out Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 10/20] sched/core: Push current task from non preferred CPU Shrikanth Hegde
2026-06-18 4:09 ` K Prateek Nayak
2026-06-18 6:05 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 11/20] sched/debug: Add migration stats due to non preferred CPUs Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 12/20] sched/debug: Create debugfs folder steal monitor Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 13/20] sched/debug: Provide debugfs to enable/disable " Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 14/20] sched/core: Introduce a simple " Shrikanth Hegde
2026-06-18 4:30 ` Yury Norov
2026-06-18 4:44 ` Shrikanth Hegde
2026-06-18 5:32 ` K Prateek Nayak
2026-06-18 6:01 ` Shrikanth Hegde
2026-06-18 6:39 ` Yury Norov
2026-06-18 6:45 ` Shrikanth Hegde
2026-06-18 7:16 ` Yury Norov
2026-06-19 6:26 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 15/20] sched/core: Compute steal values at regular intervals Shrikanth Hegde
2026-06-18 4:04 ` Yury Norov
2026-06-18 5:39 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 16/20] sched/core: Introduce default arch handling code for inc/dec preferred CPUs Shrikanth Hegde
2026-06-18 4:15 ` Yury Norov
2026-06-18 4:42 ` Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 17/20] sched/core: Handle steal values and mark CPUs as preferred Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 18/20] sched/core: Mark the direction of steal values to avoid oscillations Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 19/20] sched/debug: Add debug knobs for steal monitor Shrikanth Hegde
2026-06-17 17:41 ` [PATCH v4 20/20] sched/core: Add a few check for valid CPU in inc/dec of preferred CPUs Shrikanth Hegde
2026-06-18 4:21 ` Yury Norov
2026-06-18 4:40 ` Shrikanth Hegde
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