From: Vojtech Pavlik <vojtech@suse.cz>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Con Kolivas <kernel@kolivas.org>,
linux-kernel@vger.kernel.org, George Anzinger <george@mvista.com>,
"Martin J. Bligh" <mbligh@mbligh.org>,
Lee Revell <rlrevell@joe-job.com>,
Diego Calleja <diegocg@gmail.com>,
azarah@nosferatu.za.org, akpm@osdl.org, cw@f00f.org,
torvalds@osdl.org, christoph@lameter.org
Subject: Re: i386: Selectable Frequency of the Timer Interrupt
Date: Tue, 12 Jul 2005 18:07:17 +0200 [thread overview]
Message-ID: <20050712160717.GB8740@ucw.cz> (raw)
In-Reply-To: <Pine.LNX.4.61.0507121546160.8594@yvahk01.tjqt.qr>
On Tue, Jul 12, 2005 at 04:05:16PM +0200, Jan Engelhardt wrote:
> >> > HZ ticks/jiffie 1 second error (ppm)
> >> > ---------------------------------------------------
> >> > 100 11932 1.000015238 15.2
>
> I was not quite able to reproduce these values, probably because I got the
> math wrong. I used:
> $oneSecond = $ticksJiffie * $HZ / 1193182
> which yields 11932*100/1193182 = 1.00001508571198693912, !=1.000015238
> Math corrections welcome.
I used 1.19318[18] MHz periodic as the true clock speed - 1/3rd of the
NTSC color subcarrier frequency.
1193182 Hz is already a rounded value, and as such introduces some error
by the rounding.
It is possible the standard value is 1.1931816[6] MHz periodic, as
Richard B. Johnson corrected me, being 1/12th of 14.31818000 MHz, the
CGA dotclock.
Anyway, both 14.31818 MHz and 14.3181818 MHz crystals are being
manufactured, and thus we'll see both these numbers in the wild.
> Anyway, I've done some graphs. Intersting that the smaller the HZ, the less
> error (seen on a whole, esp. view_1k and view_8k.png) we get. 20Hz seems to
> be the 0.0 case, and 18Hz is not bad either. IIRC, DOS used 18HZ ;)
> http://jengelh.hopto.org/tick/
DOS used 65535 as the divisor (ticks/jiffie), which doesn't give an
integer HZ.
--
Vojtech Pavlik
SuSE Labs, SuSE CR
next prev parent reply other threads:[~2005-07-12 16:11 UTC|newest]
Thread overview: 201+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200506231828.j5NISlCe020350@hera.kernel.org>
2005-07-08 21:49 ` [PATCH] i386: Selectable Frequency of the Timer Interrupt Chris Wedgwood
2005-07-08 21:59 ` Andrew Morton
2005-07-08 22:05 ` Chris Wedgwood
2005-07-08 22:08 ` Linus Torvalds
2005-07-10 10:45 ` Denis Vlasenko
2005-07-08 22:22 ` Lee Revell
2005-07-08 22:33 ` Andrew Morton
2005-07-08 22:59 ` Martin J. Bligh
2005-07-08 23:03 ` Chris Wedgwood
2005-07-08 23:14 ` Martin J. Bligh
2005-07-08 23:29 ` David S. Miller
2005-07-08 23:40 ` Lee Revell
2005-07-09 17:08 ` Martin Schlemmer
2005-07-09 18:16 ` Lee Revell
2005-07-09 18:31 ` Arjan van de Ven
2005-07-09 18:33 ` Chris Wedgwood
2005-07-09 18:36 ` Lee Revell
2005-07-09 19:12 ` Andrew Morton
2005-07-09 19:16 ` Lee Revell
2005-07-09 20:30 ` randy_dunlap
2005-07-09 21:25 ` Lee Revell
2005-07-09 23:30 ` Randy Dunlap
2005-07-11 18:35 ` Martin J. Bligh
2005-07-11 13:23 ` Alan Cox
2005-07-11 14:05 ` Theodore Ts'o
2005-07-11 14:08 ` Arjan van de Ven
2005-07-11 15:18 ` Alan Cox
2005-07-12 2:13 ` Eric St-Laurent
2005-07-11 16:02 ` Chris Wedgwood
2005-07-15 12:17 ` Pavel Machek
2005-07-13 15:59 ` Bill Davidsen
2005-07-13 16:47 ` Lee Revell
2005-07-10 0:44 ` pmarques
2005-07-09 18:39 ` Diego Calleja
2005-07-09 18:41 ` Lee Revell
2005-07-09 18:49 ` Lee Revell
2005-07-09 18:50 ` Chris Wedgwood
2005-07-11 18:38 ` Martin J. Bligh
2005-07-11 20:25 ` Lee Revell
2005-07-11 20:39 ` Chris Friesen
2005-07-12 0:30 ` Lee Revell
2005-07-12 4:07 ` Martin J. Bligh
2005-07-12 4:13 ` Lee Revell
2005-07-12 4:30 ` Martin J. Bligh
2005-07-12 14:21 ` Lee Revell
2005-07-12 14:24 ` Lee Revell
2005-07-12 14:56 ` Martin J. Bligh
2005-07-12 15:00 ` Lee Revell
2005-07-12 15:08 ` Martin J. Bligh
2005-07-12 15:10 ` Lee Revell
2005-07-12 15:22 ` Martin J. Bligh
2005-07-12 19:30 ` Lee Revell
2005-07-12 20:58 ` Lee Revell
2005-07-12 22:22 ` Martin J. Bligh
2005-07-13 5:37 ` Lee Revell
2005-07-13 10:38 ` Jan Engelhardt
2005-07-13 18:42 ` High irq load (Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt) Linus Torvalds
2005-07-14 14:25 ` Peter Osterlund
2005-07-18 5:53 ` Herbert Poetzl
2005-07-12 0:38 ` [PATCH] i386: Selectable Frequency of the Timer Interrupt George Anzinger
2005-07-12 12:10 ` Vojtech Pavlik
2005-07-12 12:39 ` Con Kolivas
2005-07-12 12:52 ` Con Kolivas
2005-07-12 15:57 ` George Anzinger
2005-07-12 16:27 ` Vojtech Pavlik
2005-07-13 16:26 ` Bill Davidsen
2005-07-13 16:46 ` Lee Revell
2005-07-13 17:24 ` David Lang
2005-07-13 18:42 ` Vojtech Pavlik
2005-07-13 19:10 ` Linus Torvalds
2005-07-13 19:13 ` Lee Revell
2005-07-13 19:32 ` Dmitry Torokhov
2005-07-13 19:33 ` Martin J. Bligh
2005-07-13 20:02 ` Fernando Lopez-Lezcano
2005-07-13 20:17 ` Lee Revell
2005-07-13 20:24 ` Lee Revell
2005-07-13 20:48 ` Andrew Morton
2005-07-13 21:16 ` Chris Wedgwood
2005-07-13 21:24 ` Lee Revell
2005-07-13 21:35 ` Martin J. Bligh
2005-07-13 21:37 ` Chris Friesen
2005-07-13 21:56 ` Chris Wedgwood
2005-07-13 23:07 ` George Anzinger
2005-07-13 21:29 ` Martin J. Bligh
2005-07-13 21:30 ` Lee Revell
2005-07-13 23:41 ` dean gaudet
2005-07-14 0:07 ` Petr Vandrovec
2005-07-14 9:24 ` Jan Engelhardt
2005-07-14 14:20 ` Lee Revell
2005-07-14 18:05 ` Jan Engelhardt
2005-07-14 18:20 ` Linus Torvalds
2005-07-14 0:51 ` Chris Wedgwood
2005-07-14 1:13 ` dean gaudet
2005-07-14 1:33 ` Lee Revell
2005-07-14 1:54 ` Linus Torvalds
2005-07-14 7:42 ` Arjan van de Ven
2005-07-14 12:13 ` Vojtech Pavlik
2005-07-14 16:37 ` Linus Torvalds
2005-07-14 17:02 ` Arjan van de Ven
2005-07-14 17:21 ` Linus Torvalds
2005-07-14 19:09 ` Russell King
2005-07-14 20:06 ` Linus Torvalds
2005-07-14 20:30 ` Russell King
2005-07-15 8:15 ` Gerd Knorr
2005-07-14 20:38 ` Johannes Stezenbach
2005-07-14 17:42 ` Al Boldi
2005-07-14 19:42 ` john stultz
2005-07-14 20:13 ` Linus Torvalds
2005-07-14 20:41 ` Christoph Lameter
2005-07-14 23:03 ` Chris Wedgwood
2005-07-14 21:54 ` john stultz
2005-07-14 22:43 ` Alan Cox
2005-07-14 23:19 ` Linus Torvalds
2005-07-15 12:33 ` Alan Cox
2005-07-14 17:10 ` Chris Friesen
2005-07-14 17:24 ` Linus Torvalds
2005-07-14 19:18 ` john stultz
2005-07-14 22:37 ` Alan Cox
2005-07-14 23:13 ` Linus Torvalds
2005-07-14 23:32 ` Linus Torvalds
2005-07-15 1:17 ` Eric St-Laurent
2005-07-14 23:17 ` Lee Revell
2005-07-14 23:25 ` Linus Torvalds
2005-07-14 23:41 ` Lee Revell
2005-07-14 23:49 ` Linus Torvalds
2005-07-14 23:53 ` Lee Revell
2005-07-15 12:42 ` Bill Davidsen
2005-07-14 23:57 ` Lee Revell
2005-07-15 2:30 ` Fernando Lopez-Lezcano
2005-07-15 12:46 ` Bill Davidsen
2005-07-15 16:46 ` Fernando Lopez-Lezcano
2005-07-30 5:49 ` [GIT PATCH] ACPI patches for 2.6.13 Len Brown
2005-07-30 9:58 ` [ACPI] " Pavel Machek
2005-08-03 23:16 ` [GIT PATCH] ACPI patches for 2.6.13-rc5 Len Brown
2005-08-04 17:11 ` [GIT PATCH] ACPI patches for 2.6.13-rc5+ Len Brown
2005-08-15 20:35 ` [GIT PATCH] ACPI patch for 2.6.13-rc6 Len Brown
2005-07-14 23:50 ` [PATCH] i386: Selectable Frequency of the Timer Interrupt Lee Revell
2005-07-15 4:08 ` Con Kolivas
2005-07-15 4:17 ` Lee Revell
2005-07-15 4:54 ` Zwane Mwaikambo
2005-07-15 16:59 ` Lee Revell
2005-07-15 14:51 ` kernel
2005-07-14 18:00 ` Andrew Morton
2005-07-14 8:38 ` Ingo Molnar
2005-07-14 14:55 ` Lee Revell
2005-07-14 15:02 ` Christoph Lameter
2005-07-14 15:25 ` Lee Revell
2005-07-15 11:38 ` [OT] high precision hardware (was Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt) Paul Jakma
2005-07-15 15:57 ` Christoph Lameter
2005-07-15 16:13 ` Lee Revell
2005-07-14 2:08 ` [PATCH] i386: Selectable Frequency of the Timer Interrupt Lee Revell
2005-07-14 9:56 ` Maciej W. Rozycki
2005-07-15 0:04 ` Jesper Juhl
2005-07-15 0:15 ` Lee Revell
2005-07-15 0:17 ` Jesper Juhl
2005-07-15 0:42 ` Linus Torvalds
2005-07-15 8:41 ` Russell King
2005-07-15 0:24 ` Linus Torvalds
2005-07-15 1:40 ` Jesper Juhl
2005-07-15 2:00 ` Eric St-Laurent
2005-07-15 19:58 ` Stephen Pollei
2005-07-16 5:16 ` Eric St-Laurent
2005-07-15 2:07 ` Bill Davidsen
2005-07-15 9:36 ` Matthias Urlichs
2005-07-15 3:46 ` Jesper Juhl
2005-07-15 5:04 ` Linus Torvalds
2005-07-15 13:12 ` Jesper Juhl
2005-07-17 2:13 ` Jesper Juhl
2005-07-17 2:35 ` Lee Revell
2005-07-17 2:35 ` Nish Aravamudan
2005-07-17 3:55 ` Lee Revell
2005-07-23 23:40 ` randy_dunlap
2005-07-25 13:26 ` Vojtech Pavlik
2005-07-23 23:48 ` randy_dunlap
2005-07-23 23:52 ` Jesper Juhl
2005-07-24 12:58 ` Bill Davidsen
2005-07-15 8:44 ` Russell King
2005-07-15 15:41 ` Pavel Machek
2005-07-13 20:02 ` Diego Calleja
2005-07-13 19:35 ` Benjamin LaHaise
2005-07-13 19:41 ` Vojtech Pavlik
2005-07-13 19:53 ` Benjamin LaHaise
2005-07-14 10:04 ` Maciej W. Rozycki
2005-07-13 19:52 ` George Anzinger
2005-07-13 23:54 ` Con Kolivas
2005-07-14 0:43 ` George Anzinger
2005-07-14 10:25 ` Krzysztof Halasa
2005-07-14 12:19 ` Vojtech Pavlik
2005-07-14 21:19 ` Krzysztof Halasa
2005-07-15 1:19 ` Bill Davidsen
2005-07-12 13:30 ` Vojtech Pavlik
2005-07-12 14:05 ` Jan Engelhardt
2005-07-12 16:07 ` Vojtech Pavlik [this message]
2005-07-12 15:26 ` [PATCH] " Martin J. Bligh
2005-07-12 17:50 ` john stultz
2005-07-12 22:30 ` Nishanth Aravamudan
2005-07-12 17:56 ` john stultz
2005-07-12 0:45 ` Lee Revell
2005-07-11 13:18 ` Alan Cox
2005-07-12 12:50 Jan Engelhardt
2005-07-12 13:02 ` Richard B. Johnson
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