Multiple Tracers

[Steven Whitehouse <swhiteho@redhat.com>]

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.

Is there a solution to this which I've not spotted, or would something
along the lines of my previous patch[*] be a reasonable solution at this
stage?

Steve.

[*] http://markmail.org/message/ujkd6bre2td27pfb