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Date:   Tue, 6 Jun 2023 19:28:11 +0800
From:   Feng Tang <feng.tang@intel.com>
To:     Chris Bainbridge <chris.bainbridge@gmail.com>
CC:     <paulmck@kernel.org>, <tglx@linutronix.de>, <sboyd@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: skew message does not handle negative ns skew
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Hi,

Could you share more info about the hardware, like which generation,
how many sockets or numa nodes (output of lscpu, 'numactl -h') ?

Thanks,
Feng

On Tue, Jun 06, 2023 at 11:33:50AM +0100, Chris Bainbridge wrote:
> Hi,
> 
> I noticed this message in the log (booting latest linux master
> v6.4-rc5-2-gf8dba31b0a82):
> 
> [    1.416270] clocksource: tsc: mask: 0xffffffffffffffff max_cycles:
> 0x36c4175520f, ma
> x_idle_ns: 881590509340 ns
> [    2.087102] clocksource: timekeeping watchdog on CPU3: Marking
> clocksource 'tsc' as unstable because the skew is too large:
> [    2.087105] clocksource:                       'hpet' wd_nsec: 512006134
> wd_now: 1c0c752 wd_last: 150ea9e mask: ffffffff
> [    2.087107] clocksource:                       'tsc' cs_nsec: 511127975
> cs_now: 65279672b cs_last: 618995074 mask: ffffffffffffffff
> [    2.087108] clocksource:                       Clocksource 'tsc' skewed
> -878159 ns (18446744073708 ms) over watchdog 'hpet' interval of 512006134
> ns (512 ms)
> [    2.087110] clocksource:                       'tsc-early' (not 'tsc')
> is current clocksource.
> 
> Note: Clocksource 'tsc' skewed -878159 ns (18446744073708 ms)
> 
> It looks like this message was introduced in December 2022, in commit
> dd029269947a