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From: "Chuyi Zhou" <zhouchuyi@bytedance.com>
To: "Steven Rostedt" <rostedt@goodmis.org>
Cc: <tglx@linutronix.de>, <mingo@redhat.com>, <luto@kernel.org>,
	 <peterz@infradead.org>, <paulmck@kernel.org>,
	<muchun.song@linux.dev>,  <bp@alien8.de>,
	<dave.hansen@linux.intel.com>, <pbonzini@redhat.com>,
	 <bigeasy@linutronix.de>, <clrkwllms@kernel.org>,
	 <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 02/12] smp: Enable preemption early in smp_call_function_single
Date: Thu, 19 Mar 2026 10:30:14 +0800	[thread overview]
Message-ID: <de055dee-6ac5-401b-bf28-e06a76f060c2@bytedance.com> (raw)
In-Reply-To: <20260318101442.371c69ae@gandalf.local.home>

Hi Steve,

在 2026/3/18 22:14, Steven Rostedt 写道:
> On Wed, 18 Mar 2026 12:56:28 +0800
> "Chuyi Zhou" <zhouchuyi@bytedance.com> wrote:
> 
>> diff --git a/kernel/smp.c b/kernel/smp.c
>> index fc1f7a964616..b603d4229f95 100644
>> --- a/kernel/smp.c
>> +++ b/kernel/smp.c
>> @@ -685,11 +685,16 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
>>   
>>   	err = generic_exec_single(cpu, csd);
>>   
>> +	/*
>> +	 * @csd is stack-allocated when @wait is true. No concurrent access
>> +	 * except from the IPI completion path, so we can re-enable preemption
>> +	 * early to reduce latency.
>> +	 */
> 
> Thanks for the comment. I walked through the code and this looks fine to me.
> 
>> +	put_cpu();
>> +
>>   	if (wait)
>>   		csd_lock_wait(csd);
>>   
>> -	put_cpu();
>> -
>>   	return err;
> 
> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> 

Thanks!

> -- Steve

  reply	other threads:[~2026-03-19  2:30 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-18  4:56 [PATCH v3 00/12] Allow preemption during IPI completion waiting to improve real-time performance Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 01/12] smp: Disable preemption explicitly in __csd_lock_wait Chuyi Zhou
2026-03-18 14:13   ` Steven Rostedt
2026-03-18  4:56 ` [PATCH v3 02/12] smp: Enable preemption early in smp_call_function_single Chuyi Zhou
2026-03-18 14:14   ` Steven Rostedt
2026-03-19  2:30     ` Chuyi Zhou [this message]
2026-03-18  4:56 ` [PATCH v3 03/12] smp: Remove get_cpu from smp_call_function_any Chuyi Zhou
2026-03-18 14:32   ` Steven Rostedt
2026-03-18 15:39     ` Sebastian Andrzej Siewior
2026-03-18  4:56 ` [PATCH v3 04/12] smp: Use on-stack cpumask in smp_call_function_many_cond Chuyi Zhou
2026-03-18 14:38   ` Steven Rostedt
2026-03-18 15:55   ` Sebastian Andrzej Siewior
2026-03-19  3:02     ` Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 05/12] smp: Free call_function_data via RCU in smpcfd_dead_cpu Chuyi Zhou
2026-03-18 16:19   ` Sebastian Andrzej Siewior
2026-03-19  7:48     ` Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 06/12] smp: Enable preemption early in smp_call_function_many_cond Chuyi Zhou
2026-03-18 16:55   ` Sebastian Andrzej Siewior
2026-03-19  3:46     ` Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 07/12] smp: Remove preempt_disable from smp_call_function Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 08/12] smp: Remove preempt_disable from on_each_cpu_cond_mask Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 09/12] scftorture: Remove preempt_disable in scftorture_invoke_one Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 10/12] x86/mm: Move flush_tlb_info back to the stack Chuyi Zhou
2026-03-18 17:21   ` Sebastian Andrzej Siewior
2026-03-18 20:24     ` Nadav Amit
2026-03-18 22:28       ` Nadav Amit
2026-03-19  8:49         ` Sebastian Andrzej Siewior
2026-03-19 10:37           ` Nadav Amit
2026-03-19 10:58             ` Sebastian Andrzej Siewior
2026-03-19 13:41               ` Chuyi Zhou
2026-03-19 14:40                 ` Sebastian Andrzej Siewior
2026-03-20 14:33     ` Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 11/12] x86/mm: Enable preemption during native_flush_tlb_multi Chuyi Zhou
2026-03-18  4:56 ` [PATCH v3 12/12] x86/mm: Enable preemption during flush_tlb_kernel_range Chuyi Zhou

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