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From: Ingo Molnar <mingo@kernel.org>
To: Feng Tang <feng.tang@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>, John Stultz <john.stultz@linaro.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Fwd: [GIT PULL] timer changes for v3.10
Date: Tue, 7 May 2013 08:53:48 +0200	[thread overview]
Message-ID: <20130507065348.GF17705@gmail.com> (raw)
In-Reply-To: <20130507023853.GA2945@feng-snb>


* Feng Tang <feng.tang@intel.com> wrote:

> > is even worse than that. Machine can stay is s2ram for weeks (for a 
> > lot more if it is desktop and you do s2ram for powersaving). Also 
> > temperature of CPU varies a lot between active and s2ram states. Is 
> > TSC good enough?
> 
> Yes, I think it is relatively precise. Per our test, system time backed 
> by the S3 non stop TSC only has 1 second drift after 4 days running 
> (with mixed running and S3 states). And before using this feature, we've 
> seen many time drift problems due to the RTC HW or system FW with our 
> platforms.

Nice result ...

Is that with NTP running?

Without NTP, the TSC fast-calibration on bootup is not (expected to be) 
nearly as precise as the 1:345600 precision you've measured.

Thanks,

	Ingo

  reply	other threads:[~2013-05-07  6:53 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-30  7:43 [GIT PULL] timer changes for v3.10 Ingo Molnar
2013-04-30 15:21 ` Linus Torvalds
2013-05-01 10:53   ` Ingo Molnar
2013-05-02 10:22   ` Thomas Gleixner
2013-05-06 23:01 ` Pavel Machek
2013-05-07  0:10   ` John Stultz
     [not found]   ` <CA++bM2scosWgBpC3_LzcKYOjG4EQQzN5Vf4rZFds-5qRVRwvDQ@mail.gmail.com>
2013-05-07  2:38     ` Fwd: " Feng Tang
2013-05-07  6:53       ` Ingo Molnar [this message]
2013-05-07  7:05         ` Feng Tang
2013-05-07 16:01         ` John Stultz
2013-05-07 17:18           ` Ingo Molnar
2013-05-07 21:31           ` Pavel Machek
2013-05-07 21:39             ` John Stultz
2013-05-07 21:51               ` Pavel Machek
2013-05-08  6:44                 ` Ingo Molnar
2013-05-08 10:55                   ` Pavel Machek
2013-05-08 14:11                     ` Feng Tang
2013-05-08 14:34                     ` Thomas Gleixner
2013-05-08 19:49                       ` Pavel Machek
2013-05-09  8:59                         ` Ingo Molnar

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