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Date: Tue, 02 Jun 2009 14:28:29 -0600
From: "Chris Friesen" <cfriesen@nortel.com>
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To: wael showair <showair2003@yahoo.com>
Subject: Re: is the resolution of do_gettimeofday in usec?
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wael showair wrote:
> Hi All,
> i have board that contains MPC8555 processor with linux 2.6.27 ported to it.
> i want to use an accurate function to measure the time. i searched the
> kernel code & i found several functions but i read that the do_gettimeofday
> is the most accurate one since it has a timer resolution of usec.

You might also look at clock_gettime(), which has a theoretical accuracy
of nanoseconds.  Both this and gettimeofday are NTP-corrected if you are
synced to an NTP clock.

> my question is how this function give this accuracy while the kernel timer
> is 4msec?

The accuracy of the timestamp is not related to the tick interval.

Chris