From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: K Prateek Nayak <kprateek.nayak@amd.com>,
"Guo, Wangyang" <wangyang.guo@intel.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 11:56:52 +0530 [thread overview]
Message-ID: <868b9993-34a2-4b33-b47a-989b2c680689@linux.ibm.com> (raw)
In-Reply-To: <5e001aeb-50a8-475f-bff2-6d101e15d078@amd.com>
On 1/28/26 8:35 AM, K Prateek Nayak wrote:
> 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.
>
I think this would depend if mark_tsc_unstable happens after system boot,
specially while running kvm guest?
next prev parent reply other threads:[~2026-01-28 6:27 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
2026-01-28 6:26 ` Shrikanth Hegde [this message]
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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