linux-kernel - Re: [PATCH v2] sched/clock: Avoid false sharing for sched_clock

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Message-ID: <531cd86a-0737-40bc-a504-a016a64464f8@amd.com>
Date: Tue, 13 Jan 2026 15:44:38 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Peter Zijlstra <peterz@...radead.org>, Wangyang Guo
	<wangyang.guo@...el.com>
CC: Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann
	<dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, Ben Segall
	<bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, Valentin Schneider
	<vschneid@...hat.com>, <linux-kernel@...r.kernel.org>, Shrikanth Hegde
	<sshegde@...ux.ibm.com>, Benjamin Lei <benjamin.lei@...el.com>, Tim Chen
	<tim.c.chen@...ux.intel.com>, Tianyou Li <tianyou.li@...el.com>
Subject: Re: [PATCH v2] sched/clock: Avoid false sharing for
 sched_clock_irqtime

Hello Peter,

On 1/13/2026 3:37 PM, Peter Zijlstra wrote:
> On Tue, Jan 13, 2026 at 03:48:07PM +0800, Wangyang Guo wrote:
>> Read-mostly sched_clock_irqtime may share the same cacheline with
>> frequently updated nohz struct. Mark it as __read_mostly to avoid
>> false sharing issue.
>>
> 
> Is there a reason that thing can't be a static_key or so?

Yes, the exact case is stated in commit b9f2b29b9494
("sched: Don't define sched_clock_irqtime as static key")
https://lore.kernel.org/lkml/173961695743.10177.17683780278419896262.tip-bot2@tip-bot2/

-- 
Thanks and Regards,
Prateek