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From:   Thomas Gleixner <tglx@linutronix.de>
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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
In-Reply-To: <20230406105529.GB392176@hirez.programming.kicks-ass.net>
References: <20230406095735.0_14edn3@linutronix.de>
 <20230406105529.GB392176@hirez.programming.kicks-ass.net>
Date:   Thu, 06 Apr 2023 13:08:29 +0200
Message-ID: <87mt3lqnde.ffs@tglx>
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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