* [PATCH] linux-2.6.3_time-interpolator-fix_A0
[not found] ` <16435.3326.193311.110598@napali.hpl.hp.com>
@ 2004-02-23 19:44 ` john stultz
2004-02-23 19:55 ` David Mosberger
0 siblings, 1 reply; 2+ messages in thread
From: john stultz @ 2004-02-23 19:44 UTC (permalink / raw)
To: Andrew Morton; +Cc: Chris McDermott, ia64, lkml, David Mosberger
[Resending to Andrew and LKML]
All,
In developing the ia64-cyclone patch, which implements a cyclone based
time interpolator, I found the following bug which could cause time
inconsistencies.
In update_wall_time_one_tick(), which is called each timer interrupt, we
call time_interpolator_update(delta_nsec) where delta_nsec is
approximately NSEC_PER_SEC/HZ. This directly correlates with the changes
to xtime which occurs in update_wall_time_one_tick().
However in update_wall_time(), on a second overflow, we again call
time_interpolator_update(NSEC_PER_SEC). However while the components of
xtime are being changed, the overall value of xtime does not (nsec is
decremented NSEC_PER_SEC and sec is incremented). Thus this call to
time_interpolator_update is incorrect.
This patch removes the incorrect call to time_interpolator_update and
was found to resolve the time inconsistencies I had seen while
developing the ia64-cyclone patch.
Please consider for inclusion.
diff -Nru a/kernel/timer.c b/kernel/timer.c
--- a/kernel/timer.c Wed Feb 18 12:04:03 2004
+++ b/kernel/timer.c Wed Feb 18 12:04:03 2004
@@ -677,7 +677,6 @@
if (xtime.tv_nsec >= 1000000000) {
xtime.tv_nsec -= 1000000000;
xtime.tv_sec++;
- time_interpolator_update(NSEC_PER_SEC);
second_overflow();
}
}
^ permalink raw reply [flat|nested] 2+ messages in thread