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Date: Mon, 10 Feb 2003 17:06:59 -0500 (EST)
From: Bill Davidsen <davidsen@tmr.com>
To: Andi Kleen <ak@suse.de>
cc: lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] linux-2.5.59_getcycles_A0
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On Sat, 8 Feb 2003, Andi Kleen wrote:

> Regarding the watchdog: what it basically wants is a POSIX
> CLOCK_MONOTONIC clock. This isn't currently implemented by Linux, 
> but I expect it will be eventually because it's really useful for a lot
> of applications who just need an increasing time stamp in user space,
> and who do not want to fight ntpd for this. One example for such 
> an application is the X server who needs this for its internal 
> event sequencing.
> 
> Implementing it based on the current time infrastructure is very easy -
> you just do not add xtime and wall jiffies in, but only jiffies.
> 
> I don't think doing any special hacks and complicating get_cycles()
> for it is the right way. Just implement a new monotonic clock primitive
> (and eventually export it to user space too) 

That seems to be the right way to go, rather than slow get_cycles() have a
separate functionality which does what you need. Didn't know about
CLOCK_MONOTONIC by that name, but I agree it's useful in various places.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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