This is the mail archive of the
systemtap@sources.redhat.com
mailing list for the systemtap project.
Re: Notes from the systemtap BOF
- From: Karim Yaghmour <karim at opersys dot com>
- To: William Cohen <wcohen at redhat dot com>
- Cc: maneesh at in dot ibm dot com, "Spirakis, Charles" <charles dot spirakis at intel dot com>, systemtap at sources dot redhat dot com, Vara Prasad <prasadav at us dot ibm dot com>, Michel Dagenais <michel dot dagenais at polymtl dot ca>, Mathieu Desnoyers <compudj at krystal dot dyndns dot org>
- Date: Thu, 28 Jul 2005 10:47:42 -0400
- Subject: Re: Notes from the systemtap BOF
- Organization: Opersys inc.
- References: <2CB9B46A0690824693581340E23B4E1004A4AF6A@scsmsx401.amr.corp.intel.com> <20050728121516.GB31575@in.ibm.com> <42E8F009.6070703@redhat.com>
- Reply-to: karim at opersys dot com
William Cohen wrote:
> It would be really nice if the hardware designers provided a machine
> specific register that provide high resolution clock. This would make
> life so much easier to merge data together and create reasonable
> timelines and determine cause and effect. A sub-$100 consumer GPS can
> very accurately determine the time. Why can't a regular processor? A
> second system setable one for virtual time would also be useful.
>
> My understanding is that LTT has some support to take into account the
> possible skew between the process time stamp counters.
There may be some things the Polytechnique team is working on that I'm
not aware of (I've CC'ed Prof. Michel Dagenais who heads that team and
Mathieu who's working on the next generation visualizer there), but
there is currently little in the mainstream visualizer that does this.
However, I know that Michel had someone there that did part of his
project on measuring the clock skew using exactly what you mention: a
GPS device. Hopefully Mathieu or Michel can give us better insight as
to whether some of that work percolated back into lttv.
Karim
--
Author, Speaker, Developer, Consultant
Pushing Embedded and Real-Time Linux Systems Beyond the Limits
http://www.opersys.com || karim@opersys.com || 1-866-677-4546