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From: K Prateek Nayak <kprateek.nayak@amd.com>
To: "Guo, Wangyang" <wangyang.guo@intel.com>,
	Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: <linux-kernel@vger.kernel.org>,
	Benjamin Lei <benjamin.lei@intel.com>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	Tianyou Li <tianyou.li@intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>
Subject: Re: [PATCH v7] sched/clock: Avoid false sharing for sched_clock_irqtime
Date: Wed, 28 Jan 2026 08:35:58 +0530	[thread overview]
Message-ID: <5e001aeb-50a8-475f-bff2-6d101e15d078@amd.com> (raw)
In-Reply-To: <3b69443c-f82c-4b73-8384-2a039d730213@intel.com>

On 1/28/2026 7:49 AM, Guo, Wangyang wrote:
> Yes, when clock mark unstable through tsc_.*mark_unstable() with non-native_sched_clock, clear_sched_clock_stable won't be called, thus sched_clock_irqtime still keep enabled.
> 
> Maybe the dedicated workqueue for sched_clock_irqtime is still needed considering this case.

In that case, shouldn't tsc_init() only enable irqtime when
using_native_sched_clock()? How can tsc_init() make a call on irqtime if
TSC isn't being used as the sched_clock() ultimately?

For kvmclock, if PVCLOCK_TSC_STABLE_BIT is not set, it'll call
clear_sched_clock_stable() at kvm_sched_clock_init() but none of the
other clocksources do so we can assume once we override the sched_clock()
it is up to the sched_clock() provider to deal with the clock stability.

-- 
Thanks and Regards,
Prateek


  reply	other threads:[~2026-01-28  3:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-27  7:25 Wangyang Guo
2026-01-27 11:04 ` Shrikanth Hegde
2026-01-28  2:19   ` Guo, Wangyang
2026-01-28  3:05     ` K Prateek Nayak [this message]
2026-01-28  6:26       ` Shrikanth Hegde
2026-01-28  7:18         ` K Prateek Nayak
2026-01-28  7:32           ` Shrikanth Hegde
2026-01-28  7:50             ` K Prateek Nayak
2026-01-28  7:56               ` Shrikanth Hegde
2026-02-03  9:55 ` Vincent Guittot
2026-02-03 11:18 ` [tip: sched/core] " tip-bot2 for Wangyang Guo

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