DTrace for FreeBSD - Status Update
John Birrell
jb at what-creek.com
Fri May 26 13:03:36 PDT 2006
On Fri, May 26, 2006 at 08:48:21PM +0530, Joseph Koshy wrote:
> >But, I have a naive question. Should this be integrated in
> >some way with the hwpmc work of Joseph Koshy since I think it
> >could be useful for DTRace to get information from the CPU as
> >well.
>
> Disclaimer: I've only just started reading about DTrace.
>
> There appear to be two ways to integrate hwpmc and DTrace:
>
> - Augment the D virtual machine with a primitive that can
> read PMC values (e.g.- using RDPMC or RDMSR instructions
> on x86 CPUs). Make this primitive available
> to scripts for allocating and reading from PMCs (say
> a "pmcread()" builtin function).
>
> This approach would work well with counting mode PMCs
> (both process and system-mode counting PMCs) and would
> allow PMCs to be read at arbitrary points of time.
>
> We'll need a way of allocating system-wide & process-mode
> PMCs; this could be done in userland (in dtrace(8)).
>
> - hwpmc(4) can be augmented to be a 'DTrace provider'
> allowing D scripts to be run, say when a PC sample is
> recorded.
Before modifying the virtual machine in FreeBSD's DTrace port, it would
be best to discuss this in the "DTrace Community"
<http://www.opensolaris.org/jive/forum.jspa?forumID=7>
The Sun guys will guide us on which way they think is appropriate.
--
John Birrell
More information about the freebsd-current
mailing list