Re: Ktimer / -rt9 (+custom) monotonic_clock going backwards.

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, 2005-10-19 at 10:59 -0400, Steven Rostedt wrote:
> Hi Thomas,
> 
> I switched my custom kernel timer to use the ktimers with the prio of -1
> as you mentioned to me offline.  I set up the timer to be monotonic and
> have a requirement that the returned time is always greater or equal to
> the last time returned from do_get_ktime_mono.
> 
> Now here's the results that I got between two calls of do_get_ktime_mono
> 
> 358.069795728 secs then later 355.981483177.  Should this ever happen?

Definitely not. monotonic time must go forwards. 

> I haven't look to see if this happens in vanilla -rt10 but I haven't
> touched your ktimer code except for my logging and the patch with the
> unlock_ktimer_base (since I was based off of -rt9)

The ktimer code itself calls the timeofday code, which provides the
monotonic clock. I have no idea what might go wrong. 

Is this reproducible ?

tglx


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