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Re: Hardware Clock
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Re: Hardware Clock


  • Subject: Re: Hardware Clock
  • From: "Gerriet M. Denkmann" <email@hidden>
  • Date: Sat, 8 Jul 2006 13:00:54 +0200


On 08.07.2006, at 08:48, Ed Wynne wrote:


On Jul 8, 2006, at 1:38 AM, Gerriet M. Denkmann wrote:
The problem: whenever (B) is initialized from (A) a random value in the range -0.5 ... +0.5 seconds is added to the time.
To test: make the time (B) equal to the correct wall clock time. Sleep. Awake. Compare time to wall clock. See difference of -0.5 ... +0.5 seconds.

The hardware clock is probably only second accurate and its likely the OS only samples it once, instead of polling for the next second increment. This would save about .5s (on average) from the wakeup time.

Yes; further proof for this is the fact that the system time after awakening always starts with a full second (no fractional part).


But: if the OS can poll the hardware clock, why can't I?

Gerriet.

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  • Follow-Ups:
    • Re: Hardware Clock
      • From: Ed Wynne <email@hidden>
References: 
 >Hardware Clock (From: "Gerriet M. Denkmann" <email@hidden>)
 >Re: Hardware Clock (From: "Shawn Erickson" <email@hidden>)
 >Re: Hardware Clock (From: "Gerriet M. Denkmann" <email@hidden>)
 >Re: Hardware Clock (From: Ed Wynne <email@hidden>)

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