linux-sg2042/kernel/time
john stultz 3f4a0b917c [PATCH] i386 Time: Avoid PIT SMP lockups
Avoid possible PIT livelock issues seen on SMP systems (and reported by
Andi), by not allowing it as a clocksource on SMP boxes.

However, since the PIT may no longer be present, we have to properly handle
the cases where SMP systems have TSC skew and fall back from the TSC.
Since the PIT isn't there, it would "fall back" to the TSC again.  So this
changes the jiffies rating to 1, and the TSC-bad rating value to 0.

Thus you will get the following behavior priority on i386 systems:

tsc		[if present & stable]
hpet		[if present]
cyclone		[if present]
acpi_pm		[if present]
pit		[if UP]
jiffies

Rather then the current more complicated:
tsc		[if present & stable]
hpet		[if present]
cyclone		[if present]
acpi_pm		[if present]
pit		[if cpus < 4]
tsc		[if present & unstable]
jiffies

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-17 08:18:42 -07:00
..
Makefile [PATCH] NTP: Move all the NTP related code to ntp.c 2006-10-01 00:39:26 -07:00
clocksource.c [PATCH] time: rename clocksource functions 2006-06-26 09:58:21 -07:00
jiffies.c [PATCH] i386 Time: Avoid PIT SMP lockups 2006-10-17 08:18:42 -07:00
ntp.c [PATCH] kernel/time/ntp.c: possible cleanups 2006-10-01 00:39:27 -07:00