architecture paper draft

[William Cohen]

Frank Ch. Eigler wrote:
> Hi -
> 
> I committed a first draft version of one proposed architecture in the
> systemtap CVS repository.  Check out the "archpaper" module using
> anoncvs [1].  Or use a real ssh account so you can eventually contribute
> directly (have you signed up yet?).  Just for gags, temporarily
> (since it's such an early draft) I put formatted version of the
> LaTeX paper up at home:
> <http://web.elastic.org/~fche/systemtap.pdf>
> 
> - FChE
> 
> [1]
> cvs -d :pserver:anoncvs@sources.redhat.com:/cvs/systemtap login
> {enter "anoncvs" as the password}
> cvs -d :pserver:anoncvs@sources.redhat.com:/cvs/systemtap co archpaper
> 

General comments on the systemtap paper

Clearer to label section "3.1 Input" as "SystemTap Probe Language"

If indirection is not allow then, then how does SystemTap probe data
structures in the kernel that use pointers or arguments that are
passed in to functions as pointers (assuming using jprobes).

The language seems verbose in placing the probe. For example:

break kernel.function("sys_write")

The equivalent for DTrace would be

fbt::sys_write:entry

The first is the instrumentation provider, fbt which appears to be for 
the kernel only. For userspace there is the pid provider so the format 
would be ($1 is passed in from the command line):

pid$1::sys_write:entry


Might want to use some a keyword besides "break" to indicate placement
of probe. C already uses that keyword. Are switch-case statements not
going to be language?

-Will