Re: Multiple Tracers

Ingo Molnar
2009-04-08T13:53:45Z

* Steven Whitehouse <swhiteho@redhat.com> wrote:

> Hi,
>
> A little while back I posted a RFC patch which added gfs2 glock
> tracing to blktrace. There was a suggestion that I should look
> instead at the generic tracing code and add a new tracer, but I've
> come up with a couple of issues along the way.
>
> I think from what I can see that its only possible to run a single
> tracer at once, so running blktrace (for example) would preclude
> me from also tracing gfs2's glocks at the same time. Also, I can
> see no mechanism by which I could ensure the sequencing between
> the blktrace and glock traces other than exporting the blktrace
> sequence number, even if running multiple tracers at the same time
> was possible.

There's a recent addition: the EVENT_TRACE() facility. Would that
suit your purposes?

Ingo