From: Tony Lindgren <tony@atomide.com>
To: linux-os@analogic.com
Cc: Pavel Machek <pavel@suse.cz>, john stultz <johnstul@us.ibm.com>,
Andrea Arcangeli <andrea@suse.de>,
Zwane Mwaikambo <zwane@arm.linux.org.uk>,
Con Kolivas <kernel@kolivas.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: dynamic-hz
Date: Tue, 14 Dec 2004 15:13:00 -0800 [thread overview]
Message-ID: <20041214231300.GD31226@atomide.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0412141751590.20391@chaos.analogic.com>
* linux-os <linux-os@chaos.analogic.com> [041214 15:04]:
> On Tue, 14 Dec 2004, Pavel Machek wrote:
>
> >Hi!
> >
> >>>>The patch in question is at:
> >>>>
> >>>>http://linux-omap.bkbits.net:8080/main/user=tmlind/patch@1.2016.4.18?nav=!-|index.html|stats|!+|index.html|ChangeSet@-12w|cset@1.2016.4.18
> >>>
> >>>Wow, that's basically 8 lines of code plus driver for new
> >>>hardware... Is it really that simple?
> >>
> >>Yeah, the key things are reprogramming the timer in the idle loop
> >>based on next_timer_interrupt(), and calling timer_interrupt from
> >>other interrupts as well :)
> >>
> >>Should we try a similar patch for x86/amd64? I'm not sure which timers
> >>to use though? One should be programmable length for the interrupt,
> >>and the other continuous for the timekeeping.
> >
> >Yes, it would certainly be interesting. 5% power savings, and no
> >singing capacitors, while keeping HZ=1000. Sounds good to me.
> >
> >There are about 1000 timers available in PC, each having its own
> >quirks. CMOS clock should be able to generate 1024Hz periodic timer
> >(we currently do not use) and TSC we currently use for periodic timer
> >should be usable in single-shot mode.
> > Pavel
> >--
>
> If you use that RTC timer, it needs to be something that can be
> turned OFF. Many embedded applications use that because its the
> only timer that the OS doesn't muck with. It also has very low
> noise which makes in a good timing source for IIR filters for
> high precision, low data-rate data acquisition (like 24 bits).
OK, thanks for the information. That could be the continuous timer
then, and TSC the periodic timer.
> Since it generates an edge, its interrupt can't be shared.
> I certainly hope that you don't use it. One can read the
> time without disturbing the interrupt rate. One just
> needs to use the existing rtc_lock and not spin with
> the lock being held.
Yeah, the timer update would be just a read from the RTC timer.
> Currently the kernel RTC software allocates the RTC interrupt
> even though it doesn't use it. This makes it necessary to
> compile the RTC as a module and then remove it when another
> driver needs to use the RTC interrupt source.
The interrupt could be used for timer wrap only.
Tony
next prev parent reply other threads:[~2004-12-15 0:18 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 ` Tony Lindgren [this message]
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
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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