Re: Some notes on translation

[Tom Zanussi <zanussi at us dot ibm dot com>]

Martin Hunt writes:
 > On Fri, 2005-02-25 at 10:13 -0600, Tom Zanussi wrote:
 > 
 > > 
 > > OK, I certainly don't want to duplicate anything you were working on
 > > or were planning to work on.  Is there anything in what I've outlined
 > > that isn't already being covered by you or Frank or Will (or someone
 > > else on the list)?  If not, that's fine - I can easily find something
 > > else to work on...
 > 
 > The netlink API.  We will need that soon. I could also come up with a
 > list of additional runtime functions that I know will be needed but are
 > not implemented.  For example, stack dumps. 

OK, sounds like the netlink API is what I'll focus on for the time
being.

BTW, what's the thinking on stack dumps?  There's already code in the
kernel for doing that - dump_stack(), but it's hard-coded to use
printk.  If that code could be made to print into a separate buffer
instead, it could be re-used for systemtap, but I doubt a change like
that would be accepted into the kernel.

One of the really nifty things I thought DTrace did was allow a stack
trace to be used as a hash key - you could for instance keep a counter
in each hash entry and dump the keys to get an idea of the relative
frequencies of particular execution paths to a given function.

[...]

 > 
 > We need both an underlying API, which would be part of the runtime, as
 > well as a userspace API.  There are also language concerns.  How do the
 > systemtap programs indicate where output goes and how it is
formatted?

Good question - I'll have to think about that and make sure the API
addresses it.

Thanks,

Tom