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Re: Host Time epoch

At 12:38 PM -0800 2/10/05, Steve Checkoway wrote:
On Feb 10, 2005, at 12:21 PM, John Iversen wrote:
Sorry, I'm not aware of this issue, but it's of interest to me, and is rather fundamental. Would you mind elaborating? What is the nature of the non-monotonicity--I can't imagine you mean actual reversals in the host time, I hope. Instead, do you mean that the rate of increase of the HostTime is variable, so it drifts away from 'real time'? How large is the effect in your experience?

Oh no. I mean non-monotonicity. Time does indeed move backward. I filed a bug report quite a while ago and I was told (eventually) that it was fixed in some later version of the OS.

Was this on a dual processor system?

This is just a guess, but the clock is probably a hardware register in the CPUs; therefore, it is probably per cpu. With most hardware, it's nearly impossible to reset the clocks to zero simultaneously; so, there will almost always be a slight offset between the clocks on different CPUs.

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References: 
 >Host Time epoch (From: Geoff Schmidt <email@hidden>)
 >Re: Host Time epoch (From: Jeff Moore <email@hidden>)
 >Re: Host Time epoch (From: Steve Checkoway <email@hidden>)
 >Re: Host Time epoch (From: John Iversen <email@hidden>)
 >Re: Host Time epoch (From: Steve Checkoway <email@hidden>)



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