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From: Chris Friesen <cfriesen@nortelnetworks.com>
To: Linux kernel <linux-kernel@vger.kernel.org>
Subject: question on update_wall_time_one_tick()
Date: Thu, 07 Oct 2004 14:13:45 -0600	[thread overview]
Message-ID: <4165A379.7030706@nortelnetworks.com> (raw)


If we call update_wall_time_one_tick(), with a mode of ADJ_OFFSET_SINGLESHOT, 
the offset can be up to +/-512000 usec.

However, in update_wall_time_one_tick(), the offset adjustment each tick is 
limited to the range of -tickadj < x < tickadj.  On many current systems, 
tickadj is 1.  Thus, a large adjustment takes a *long* time.

While we are doing this offset change, if someone else requests another offset, 
it will totally overwrite any unapplied portion of the offset from the previous 
call:

	/* Changes by adjtime() do not take effect till next tick. */
	if (time_next_adjust != 0) {
		time_adjust = time_next_adjust;
		time_next_adjust = 0;
	}

Thus, doing an offset of +512000, immediately followed by an offset of -512000, 
will leave you with a significant negative offset.

Is this the desired behaviour?

Chris

             reply	other threads:[~2004-10-07 20:17 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-07 20:13 Chris Friesen [this message]
2004-10-07 20:32 ` question on update_wall_time_one_tick() -- doh! Chris Friesen

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