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From: Andi Kleen <ak@muc.de>
To: lkml@cl.domainfactory-kunde.de
Cc: Clemens Ladisch <clemens@ladisch.de>,
	Andrew Morton <akpm@osdl.org>,
	Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
	Vojtech Pavlik <vojtech@suse.cz>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] HPET RTC emulation: add watchdog timer
Date: 9 Jan 2006 21:32:25 +0100
Date: Mon, 9 Jan 2006 21:32:25 +0100	[thread overview]
Message-ID: <20060109203225.GA93253@muc.de> (raw)
In-Reply-To: <1136829634.43c2a4c2e0997@www.domainfactory-webmail.de>

On Mon, Jan 09, 2006 at 07:00:34PM +0100, lkml@cl.domainfactory-kunde.de wrote:
> Andi Kleen wrote:
> > On Mon, Jan 09, 2006 at 04:43:50PM +0100, Clemens Ladisch wrote:
> > > To prevent the emulated RTC timer from stopping when interrupts
> > > are disabled for too long, implement the watchdog timer to
> > > restart it when needed.
> >
> > The interrupt handler should just read the time (it likely
> > has to do that anyways)
> 
> Not in the current implementation.

The standard HPET interrupt in x86-64 does this already at least.

> > and check for that directly.
> 
> I want to avoid the read altogether because the round trip to the
> south bridge is rather slow (1.5 microseconds with VIA chipsets).

You can use the TSC to detect it too, but it might be unreliable.

-Andi


  reply	other threads:[~2006-01-09 20:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-09 15:43 [PATCH] HPET RTC emulation: add watchdog timer Clemens Ladisch
2006-01-09 16:15 ` Clemens Ladisch
2006-01-09 16:41 ` Andi Kleen
2006-01-09 18:00   ` lkml
2006-01-09 20:32     ` Andi Kleen [this message]
2006-01-10  8:27       ` Clemens Ladisch

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