Re: Linux kernel marker questions

[David Smith <dsmith at redhat dot com>]

Mike Mason wrote:
> David,
>
> Is there enough marker support in CVS now that we can write scripts 
> against it?  I tried using the latest CVS against a kernel with a few 
> markers, but I'm seeing errors.
>
> Here's the script:
> global sem_up_cnt
> probe kernel.mark("sem_up") { sem_up_cnt++ }
> probe end { printf("sem_up_cnt = %d\n", sem_up_cnt)}
>
> Here's the marker I'm trying to access in __up() in semaphore-sleepers.c:
>
> MARK(sem_down, "%ul", (unsigned long) sem);
>
> Here are the errors I'm seeing:
>
> semantic error: bad __markers_string section?
> semantic error: no match for probe point while resolving probe point 
> kernel.mark("sem_up")
>
> Should this work yet?

Yes it should work - depending on which version of Mathieu's patches 
you've got.  I've bet we've got differing versions if you are getting 
the "bad __markers_string section" message.  I've been using the version 
of Mathieu's patches that Andrew Morton has.  I can send you a copy of 
the patches I've been using if you'd like.

One more thing - your marker is called "sem_down", but you look to be 
putting a probe on "sem_up"...

--
David Smith
dsmith@redhat.com
Red Hat
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