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From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Pavel Tatashin <pasha.tatashin@oracle.com>
Subject: Re: [RFC] tick_sched_timer() is not properly aligned, fixed by chance
Date: Thu, 06 Apr 2023 13:08:29 +0200	[thread overview]
Message-ID: <87mt3lqnde.ffs@tglx> (raw)
In-Reply-To: <20230406105529.GB392176@hirez.programming.kicks-ass.net>

On Thu, Apr 06 2023 at 12:55, Peter Zijlstra wrote:
> On Thu, Apr 06, 2023 at 11:57:35AM +0200, Sebastian Andrzej Siewior wrote:
>
>> The tick_sched_timer story is that it uses ktime_get() to set the
>
> But but but, ktime_get() does not use sched_clock(), it has it's own TSC
> reader.

Correct and at that point during early boot the clocksource which feeds
ktime_get() should be jiffies and not some other random clocksource.

Sebastian, can you please evaluate which clocksource is used for
ktime_get() at the point where the first clock event device is set up?

Thanks,

        tglx



  reply	other threads:[~2023-04-06 11:08 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-06  9:57 [RFC] tick_sched_timer() is not properly aligned, fixed by chance Sebastian Andrzej Siewior
2023-04-06 10:55 ` Peter Zijlstra
2023-04-06 11:08   ` Thomas Gleixner [this message]
2023-04-06 15:02     ` Sebastian Andrzej Siewior
2023-04-06 17:13       ` Thomas Gleixner
2023-04-18 12:26         ` [PATCH] timekeeping: Align tick_sched_timer() with the HZ tick Sebastian Andrzej Siewior
2023-06-13 22:59           ` [PATCH] timekeeping: Align tick_sched_timer() with the HZ tick. -- regression report Mathias Krause
2023-06-15  9:03             ` Richard W.M. Jones
2023-06-15 11:40               ` Mathias Krause
2023-06-15  9:22             ` Sebastian Andrzej Siewior
2023-06-16 18:53             ` [tip: timers/urgent] tick/common: Align tick period during sched_timer setup tip-bot2 for Thomas Gleixner
2023-04-18 13:14 ` [tip: timers/core] tick/common: Align tick period with the HZ tick tip-bot2 for Sebastian Andrzej Siewior

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