linux-kernel - Re: [PATCH 01/15] sched/idle: Handle offlining first in idle loop

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Message-ID: <ec1fbc52-3e72-4a0f-954c-9ecf581f9e39@amd.com>
Date: Tue, 20 Jan 2026 09:56:12 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Frederic Weisbecker <frederic@...nel.org>, Peter Zijlstra
	<peterz@...radead.org>
CC: LKML <linux-kernel@...r.kernel.org>, "Christophe Leroy (CS GROUP)"
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	<linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 01/15] sched/idle: Handle offlining first in idle loop

Hello Frederic, Peter,

On 1/20/2026 2:34 AM, Frederic Weisbecker wrote:
> Le Mon, Jan 19, 2026 at 01:53:47PM +0100, Peter Zijlstra a écrit :
>> On Fri, Jan 16, 2026 at 03:51:54PM +0100, Frederic Weisbecker wrote:
>>
>>>  kernel/sched/idle.c | 11 ++++++-----
>>>  1 file changed, 6 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
>>> index c174afe1dd17..35d79af3286d 100644
>>> --- a/kernel/sched/idle.c
>>> +++ b/kernel/sched/idle.c
>>> @@ -260,6 +260,12 @@ static void do_idle(void)
>>>  {
>>>  	int cpu = smp_processor_id();
>>>  
>>> +	if (cpu_is_offline(cpu)) {
>>
>> Does it make sense to make that: if (unlikely(cpu_is_offline(cpu))) ?
> 
> Yes indeed!

nit. but don't we inherit it from:

#define cpu_is_offline(cpu)     unlikely(!cpu_online(cpu))

so it will end up being annotated with unlikely() no?

-- 
Thanks and Regards,
Prateek