Re: [RFC][PATCH] linux-2.5.59_getcycles_A0

From: Bill Davidsen (
Date: Mon Feb 10 2003 - 17:06:59 EST

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 <>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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