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From: Vojtech Pavlik <vojtech@suse.cz>
To: Jonas Diemer <diemer@gmx.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: VIA 686 timer bugfix incomplete
Date: Thu, 8 Nov 2001 21:08:40 +0100	[thread overview]
Message-ID: <20011108210840.A6266@suse.cz> (raw)
In-Reply-To: <20011107211445.A2286@suse.cz> <Pine.LNX.4.05.10111080917140.19515-100000@marina.lowendale.com.au> <20011108090215.G3708@suse.cz> <20011108102124.31ca040f.diemer@gmx.de>
In-Reply-To: <20011108102124.31ca040f.diemer@gmx.de>; from diemer@gmx.de on Thu, Nov 08, 2001 at 10:21:24AM +0100

On Thu, Nov 08, 2001 at 10:21:24AM +0100, Jonas Diemer wrote:

> Well, then maybe Vojtech's suggestion is best: use RTC for timing, not the
> chipset...
> as to my knowledge, every i38 system has a standard RTC, so why not use this? or
> even better: make an option in the config to choose whether use RTC or the
> chipset.

There is a little problem with RTC, though:

While you can set it up to generate interrupts at say 1024 Hz, you can't
read any value of how much time passed since last interrupt. You can do
this on the PIT (i8253), and this is the part that is buggy.

TSC is perfect, precise and accurate, but not reliable in long term.
Some CPUs do thermal throttling, notebooks play with CPU speed, etc,
etc. And it's not synchronized to any interrupt source.

Ugly, ugly, ugly is the PC architecture.

-- 
Vojtech Pavlik
SuSE Labs

  reply	other threads:[~2001-11-08 20:09 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-11-07 11:50 VIA 686 timer bugfix incomplete Jonas Diemer
2001-11-07 12:15 ` Alan Cox
2001-11-07 19:25   ` Vojtech Pavlik
2001-11-07 19:48     ` Jonas Diemer
2001-11-07 20:14       ` Vojtech Pavlik
2001-11-07 22:32         ` Neale Banks
2001-11-08  8:02           ` Vojtech Pavlik
2001-11-08  9:21             ` Jonas Diemer
2001-11-08 20:08               ` Vojtech Pavlik [this message]
     [not found]                 ` <20011108221751.5273484e.diemer@gmx.de>
2001-11-08 21:22                   ` Vojtech Pavlik
2001-11-08 21:30                 ` george anzinger
2001-11-08 23:30                   ` Alan Cox
2001-11-09  8:34                     ` Vojtech Pavlik
2001-11-09 17:21                     ` george anzinger
2001-11-07 19:29   ` Steve Underwood
2001-11-08 20:11     ` Vojtech Pavlik
2001-11-09  2:57       ` Steve Underwood
  -- strict thread matches above, loose matches on Subject: below --
2001-11-09 19:19 Grover, Andrew

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