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From: Venkatesh Pallipadi <venki@google.com>
To: john stultz <johnstul@us.ibm.com>
Cc: jean-philippe francois <jp.francois@cynove.com>,
	Lin Ming <lin@ming.vg>, "H. Peter Anvin" <hpa@zytor.com>,
	linux-acpi@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	jslaby@suse.cz
Subject: Re: System time drifts when processor idle.
Date: Fri, 27 Aug 2010 17:10:19 -0700	[thread overview]
Message-ID: <AANLkTi=8MXx9L0+V-JqXoO5PCWq5EPRW9fqpr913OTyC@mail.gmail.com> (raw)
In-Reply-To: <1282932708.1946.8.camel@work-vm>

On Fri, Aug 27, 2010 at 11:11 AM, john stultz <johnstul@us.ibm.com> wrote:
> On Fri, 2010-08-27 at 16:12 +0200, jean-philippe francois wrote:
>> My Timekeeping bug is still present, here is an updated script and log.
>> I am willing to make test, but I don't know what kind of debugging
>> info is needed.
>>
>> cat /sys/devices/system/clocksource/clocksource0/available_clocksource
>> hpet acpi_pm
>> cat /sys/devices/system/clocksource/clocksource0/current_clocksource
>> hpet
>
> Huh. hpet was not what I would have expected.
>
>
> So first, two experiments:
>
> 1) Does booting with "clock=acpi_pm" cause the issue to disappear?
>
> 2) Does booting with "nohz=off" cause the issue to disappear?
>
>
> Venkatesh: You have any experience with HPETs that halt in idle?
>

No. Haven't seen anything like this before with HPET.

The jump was

system | hardware(RTC)
15:48:43 | ven. 27 août 2010 15:48:44 CEST  -0.985908 secondes
15:49:04 | ven. 27 août 2010 15:54:04 CEST  -0.032800 secondes

We lost ~300 seconds and from dmesg
hpet0: 3 comparators, 64-bit 14.318180 MHz counter

Which is close to 2^32 HPET ticks. So, looks like we have some 32 bit
wraparound somewhere..

Thanks,
Venki

  reply	other threads:[~2010-08-28  0:10 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-20  8:55 System time drifts when processor idle jean-philippe francois
2010-08-21  3:58 ` Lin Ming
2010-08-21  3:58   ` Lin Ming
2010-08-23  8:46   ` jean-philippe francois
2010-08-23  8:46     ` jean-philippe francois
2010-08-23 22:17     ` john stultz
2010-08-23 22:17       ` john stultz
2010-08-24  7:08       ` jean-philippe francois
2010-08-27 14:12         ` jean-philippe francois
2010-08-27 18:11           ` john stultz
2010-08-28  0:10             ` Venkatesh Pallipadi [this message]
2010-08-28  1:09               ` john stultz
2010-08-28  1:09                 ` john stultz
2010-08-28 12:45                 ` jean-philippe francois
2010-08-28 15:19                   ` Venkatesh Pallipadi
2010-09-02 11:45                     ` jean-philippe francois
2010-08-30  8:03                 ` jean-philippe francois
2010-09-03 12:23             ` jean-philippe francois
2010-09-09 17:42               ` john stultz
2010-09-13 13:04                 ` jean-philippe francois
2010-09-13 13:04                   ` jean-philippe francois
2010-12-06 12:55                   ` jean-philippe francois
2010-12-06 12:55                     ` jean-philippe francois

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