[ltt-dev] trace_clock_update() spinning

[Mike McTernan]

* Mathieu Desnoyers wrote:
> - Does your architecture support power management sleep modes ? If
yes,
> does the cycle counter stop in sleep modes ?
> - Does your architecture support dynamic ferquency scaling ?

Yes and yes and yes.  So as per your paper on exotic embedded
architectures it would need to use a timer to work out real time after a
sleep period like on OMAP3.  Making that stuff generic (like the 32 to
64 code) would be great.

Luckily in my application we disable DVFS and power management so this
is ok.

Alternatively i.MX51 has a programmable timer that runs reasonably fast
(66.5MHz on my setup) and is independent of power saving.  It's called
the EPIT, and I had that working too, but used the cycle count for
greater resolution and for it's similarities with OMAP3.

> - Would you agree for me to integrate it in the lttng project and
transfer
> non-exclusive relicensing rights to the LTTng maintainer ? Basically,
> the idea is to release it under dual GPLv2/LGPLv2.1 licenses, but I
> start to think that it might be just easier to use the gdb approach
for
> LTTng contributions, where the project maintainers have the freedom to
> decide license changes. 
 
The patch is small and unspecial.  I'd be happy to reassign the
copyright in this case.  

> This way we would not have to ask permission from everyone if we need
to
> do a license change for the LTTng project overall.

I wouldn't be too happy with that if I were to submit something
substantial.  

Kind Regards,

Mike