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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.
   */


  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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