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
next 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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