[Ksummit-2008-discuss] DTrace

Christoph Hellwig hch at lst.de
Sun Jun 29 01:40:02 PDT 2008

On Sat, Jun 28, 2008 at 12:56:05PM +0530, Ananth N Mavinakayanahalli wrote:
> > ptrace, it won't help you anything at all right now.  uprobes is very
> > basic infrastructure that in theory allows doing some kprobes-like
> > probes on userspace processes.  It would be a building block to
> > implement something like this, but in the current form is far from
> > what's needed.
> Right, it is a start though. We are awaiting utrace's acceptance upstream
> after which we'll post the uprobes patches too.

Actually the uprobes code that has been floating around for a while is
the completely wrong approach.   The need to generated a kernel module
that needs deeply internal VM and task management details just to
perform tracing of userspace application code is wrong.  This whole
approach needs to go back to the drawing board.  I still haven't found a
good explanation of why the actual tracing code even has to execute in
kernelspace with all the associated risk of bugs and security problems
while it would be much easier to run the actual tracing data aquisition
in userspace where it belongs.

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