From: Andrea Arcangeli <andrea@suse.de>
To: Pavel Machek <pavel@suse.cz>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>,
Con Kolivas <kernel@kolivas.org>,
linux-kernel@vger.kernel.org
Subject: Re: Time goes crazy in 2.6.9 after long cli [was Re: USB making time drift]
Date: Thu, 16 Dec 2004 12:13:43 +0100 [thread overview]
Message-ID: <20041216111343.GI28286@dualathlon.random> (raw)
In-Reply-To: <20041216011549.GD6285@elf.ucw.cz>
On Thu, Dec 16, 2004 at 02:15:49AM +0100, Pavel Machek wrote:
> Okay, I have good news and bad news. Bad news is that it is broken on
> my machine, too. Good news is that breakage is not at all subtle.
Well, I was pretty sure it was reproducible since the PIT and TSC are
standard hw in all machines, it's just the excessive usb irq latency
that triggers only in a few machines like my firewall (only with
HZ=1000).
My suggestion is that first we fix the accuracy of this, and *then* we
consider switching to a one-short timer.
Fixing this is possible as well by using only the TSC accuracy to
account for system time, and not to use anymore the PIT accuracy as
source of accuracy for system time. But then any error calibration while
we transfer the accuracy of the PIT to the TSC, will propagate in a
cumulative way over time. So it's not clear to me we can do that safely.
The PIT is designed everywhere to be accurate for system time.
next prev parent reply other threads:[~2004-12-16 11:14 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-11 14:23 dynamic-hz Andrea Arcangeli
2004-12-11 14:50 ` dynamic-hz Zwane Mwaikambo
2004-12-12 6:57 ` dynamic-hz Andrea Arcangeli
2004-12-11 21:41 ` dynamic-hz Jan Engelhardt
2004-12-12 16:35 ` dynamic-hz Pavel Machek
2004-12-12 22:23 ` dynamic-hz Andrea Arcangeli
2004-12-12 23:36 ` dynamic-hz Con Kolivas
2004-12-12 23:42 ` dynamic-hz Pavel Machek
2004-12-13 0:09 ` dynamic-hz Con Kolivas
2004-12-13 8:37 ` dynamic-hz Jan Engelhardt
2004-12-13 10:43 ` dynamic-hz Pavel Machek
2004-12-13 11:08 ` dynamic-hz Andrea Arcangeli
2004-12-13 19:36 ` dynamic-hz john stultz
2004-12-12 23:43 ` dynamic-hz Andrea Arcangeli
2004-12-13 0:18 ` dynamic-hz Con Kolivas
2004-12-13 0:27 ` dynamic-hz Andrea Arcangeli
2004-12-13 1:50 ` dynamic-hz Zwane Mwaikambo
2004-12-13 11:28 ` dynamic-hz Andrea Arcangeli
2004-12-13 12:43 ` dynamic-hz Pavel Machek
2004-12-13 12:58 ` dynamic-hz Andrea Arcangeli
2004-12-13 19:12 ` dynamic-hz Pavel Machek
2004-12-13 20:34 ` dynamic-hz john stultz
2004-12-13 20:49 ` dynamic-hz Pavel Machek
2004-12-14 2:04 ` dynamic-hz Andrea Arcangeli
[not found] ` <20041214013924.GB14617@atomide.com>
2004-12-14 9:37 ` dynamic-hz Pavel Machek
2004-12-14 21:18 ` dynamic-hz Tony Lindgren
2004-12-14 22:06 ` dynamic-hz Pavel Machek
2004-12-14 23:00 ` dynamic-hz linux-os
2004-12-14 23:13 ` dynamic-hz Tony Lindgren
2004-12-22 20:02 ` dynamic-hz Tony Lindgren
2004-12-14 23:04 ` dynamic-hz Tony Lindgren
2004-12-14 2:46 ` dynamic-hz Andrea Arcangeli
2004-12-14 19:24 ` dynamic-hz john stultz
2004-12-14 2:36 ` dynamic-hz Andrea Arcangeli
2004-12-14 9:39 ` dynamic-hz Pavel Machek
2004-12-14 9:59 ` dynamic-hz Pavel Machek
2004-12-14 15:25 ` dynamic-hz Andrea Arcangeli
2004-12-14 22:02 ` USB making time drift [was Re: dynamic-hz] Pavel Machek
2004-12-14 23:16 ` Andrea Arcangeli
2004-12-15 2:59 ` Gene Heskett
2004-12-15 9:17 ` Andrea Arcangeli
2004-12-15 16:44 ` Gene Heskett
2004-12-15 18:20 ` Andrea Arcangeli
2004-12-16 1:59 ` Gene Heskett
2004-12-16 11:30 ` Andrea Arcangeli
2004-12-16 12:50 ` Alan Cox
2004-12-15 20:16 ` Pavel Machek
2004-12-16 2:02 ` Gene Heskett
2004-12-15 17:03 ` Gene Heskett
2004-12-15 17:48 ` Tim Schmielau
2004-12-16 2:03 ` Gene Heskett
2004-12-16 0:58 ` Pavel Machek
2004-12-16 2:33 ` john stultz
2004-12-16 1:15 ` Time goes crazy in 2.6.9 after long cli [was Re: USB making time drift] Pavel Machek
2004-12-16 11:13 ` Andrea Arcangeli [this message]
2004-12-16 12:49 ` Alan Cox
2004-12-13 14:50 ` dynamic-hz Zwane Mwaikambo
2004-12-13 7:43 ` dynamic-hz Stefan Seyfried
2004-12-13 13:58 ` dynamic-hz Russell King
2004-12-13 14:14 ` dynamic-hz Russell King
2004-12-13 14:52 ` dynamic-hz Alan Cox
2004-12-13 16:23 ` dynamic-hz Russell King
2004-12-13 17:53 ` dynamic-hz Michael Buesch
2004-12-13 18:04 ` dynamic-hz Russell King
2004-12-13 19:04 ` dynamic-hz Pavel Machek
2004-12-13 20:11 ` dynamic-hz Russell King
2004-12-14 0:16 ` dynamic-hz Eric St-Laurent
2004-12-15 18:04 ` dynamic-hz Alan Cox
2004-12-15 19:54 ` dynamic-hz linux-os
2004-12-16 2:17 ` dynamic-hz Gene Heskett
2004-12-16 12:42 ` dynamic-hz linux-os
2004-12-17 20:12 ` dynamic-hz H. Peter Anvin
2004-12-16 9:10 ` dynamic-hz Gabriel Paubert
2004-12-16 12:17 ` dynamic-hz Geert Uytterhoeven
2004-12-16 14:00 ` dynamic-hz Mitchell Blank Jr
2004-12-13 15:30 ` dynamic-hz Zwane Mwaikambo
2004-12-13 15:59 ` dynamic-hz Russell King
2004-12-13 16:14 ` dynamic-hz Pavel Machek
2004-12-13 16:06 ` dynamic-hz Pavel Machek
2004-12-13 16:19 ` dynamic-hz Jan Engelhardt
2004-12-13 8:29 ` dynamic-hz Jan Engelhardt
2004-12-14 22:54 ` dynamic-hz Lee Revell
2004-12-14 23:38 ` dynamic-hz Chris Friesen
2004-12-15 8:32 ` dynamic-hz Jan Engelhardt
2004-12-13 11:02 ` dynamic-hz Andrew Morton
2004-12-13 11:17 ` dynamic-hz Andrea Arcangeli
2004-12-13 11:25 ` dynamic-hz Andrew Morton
2004-12-13 11:47 ` dynamic-hz Andrea Arcangeli
2004-12-14 3:56 ` dynamic-hz Nish Aravamudan
2004-12-14 3:54 ` dynamic-hz Nish Aravamudan
2004-12-14 4:29 ` dynamic-hz Andrew Morton
2004-12-14 5:25 ` dynamic-hz Nish Aravamudan
2004-12-17 20:10 ` dynamic-hz Nish Aravamudan
2004-12-14 10:01 ` dynamic-hz Domen Puncer
2004-12-14 16:56 ` dynamic-hz Nish Aravamudan
2004-12-14 14:23 ` dynamic-hz linux-os
2004-12-14 16:54 ` dynamic-hz Nish Aravamudan
2004-12-14 17:15 ` dynamic-hz Andrea Arcangeli
2004-12-14 17:42 ` dynamic-hz Nish Aravamudan
2004-12-14 18:29 ` dynamic-hz Andrea Arcangeli
2004-12-14 19:00 ` dynamic-hz Nish Aravamudan
2004-12-14 18:22 ` dynamic-hz linux-os
2004-12-14 18:38 ` dynamic-hz Andrea Arcangeli
2004-12-14 18:50 ` dynamic-hz Pavel Machek
2004-12-13 11:19 ` dynamic-hz Hans Kristian Rosbach
2004-12-13 11:22 ` dynamic-hz Pavel Machek
2004-12-13 11:39 ` dynamic-hz Andrea Arcangeli
2004-12-13 12:51 ` dynamic-hz Hans Kristian Rosbach
2004-12-13 13:01 ` dynamic-hz Andrea Arcangeli
2004-12-13 13:02 ` dynamic-hz Andrea Arcangeli
2004-12-13 15:06 ` dynamic-hz Geert Uytterhoeven
2004-12-13 16:12 ` dynamic-hz Pavel Machek
2004-12-13 16:14 ` dynamic-hz Geert Uytterhoeven
2004-12-14 4:06 ` dynamic-hz Nish Aravamudan
2004-12-14 4:05 ` dynamic-hz Nish Aravamudan
2004-12-13 11:33 ` dynamic-hz Andrea Arcangeli
2004-12-13 14:38 ` dynamic-hz Zwane Mwaikambo
2004-12-13 12:00 ` dynamic-hz Alan Cox
2004-12-13 15:52 ` dynamic-hz Andrea Arcangeli
2004-12-14 22:28 ` dynamic-hz Lee Revell
2004-12-14 22:40 ` dynamic-hz Con Kolivas
2004-12-14 22:50 ` dynamic-hz Lee Revell
2004-12-13 20:26 ` dynamic-hz Olaf Hering
2004-12-13 22:41 ` dynamic-hz Andrea Arcangeli
2004-12-13 20:56 ` dynamic-hz john stultz
2004-12-13 22:21 ` dynamic-hz Andrea Arcangeli
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