Re: [PATCH] printk, allow different timestamps for printk.time

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] printk, allow different timestamps for printk.time
Date	2016-01-27 10:50 +0100
Message-ID	<qVuTE-1ws-3@gated-at.bofh.it> (permalink)
References	<qUR5T-5RR-3@gated-at.bofh.it> <qViz8-10v-9@gated-at.bofh.it> <qViSv-1iC-25@gated-at.bofh.it>
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On Tue, 26 Jan 2016, Prarit Bhargava wrote:
> On 01/26/2016 03:34 PM, Thomas Gleixner wrote:
> > Just for the record: The fast timekeeper stops across the inner workings of
> > suspend/resume. But I think that doesn't matter much.
> 
> I've had to debug s/r before using the sysfs interface.  It is nice to have that
> with a proper timestamp because a lot of the failures are in the driver suspend
> and resume paths.  I could easily change the options to:

The timekeeper suspends/resumes in the syscore section, so the driver part is
not affected.

> 0 = disable
> 1 = local clock (which along with 0 would maintain the current state of things)
> 2 = monotonic
> 3 = real

Yes, that works.

Btw, you need to document, that REAL can occasionally provide a wrong value on
32bit machines in case that a concurrent update of the realtime offset happens
(settimeofday, leap seconds ...). That's because we access real_offset w/o the
seqcount protection. It's probably hard to achieve, but it might happen.

Thanks,

	tglx

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[PATCH] printk, allow different timestamps for printk.time Prarit Bhargava <prarit@redhat.com> - 2016-01-25 16:20 +0100
  Re: [PATCH] printk, allow different timestamps for printk.time Thomas Gleixner <tglx@linutronix.de> - 2016-01-26 21:40 +0100
    Re: [PATCH] printk, allow different timestamps for printk.time Prarit Bhargava <prarit@redhat.com> - 2016-01-26 22:00 +0100
      Re: [PATCH] printk, allow different timestamps for printk.time Thomas Gleixner <tglx@linutronix.de> - 2016-01-27 10:50 +0100

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