This is the mail archive of the systemtap@sourceware.org mailing list for the systemtap project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: script(s) for tracking execution paths


William Cohen writes:
 > Tom Zanussi wrote:
 > > Hi,
 > > 
 > > I've been having some fun playing around with maps keyed on stack
 > > traces (very cool to be able to do this) and have checked into
 > > systemtap.samples a systemtap script (kmalloc-stacks.stp) and a perl
 > > script (kmalloc-top) that in combination continuously track the
 > > different execution paths to kmalloc().  It keeps counts of the
 > > different execution paths in a systemtap hash, and periodically dumps
 > > the hash contents (and clears the hash table) to the perl script,
 > > which rehashes them in user space.  At the end of the run (Ctrl-C), it
 > > sorts the accumulated hash table and filters out any stacks that
 > > contain any of the user-supplied regexps (-e option), which helps cut
 > > down on noise e.g.
 > > 
 > > # ./kmalloc-top -e sys_select,alloc_skb
 > > 
 > > Here's an example of the output (gathered over a kernel compile):
 > 
 > Hi Tom, I have been playing around with the kmalloc example you checked 
 > in. When running it, I have seen a couple panics like the one in the 
 > photo at:
 > 
 > http://people.redhat.com/wcohen/100_0405.jpg
 > 
 > This is on a pentium III machine running the rawhide with the current 
 > kernel:
 > 
 > Linux trek.devel.redhat.com 2.6.13-1.1555_FC5smp #1 SMP Wed Sep 14 
 > 15:59:49 EDT 2005 i686 i686 i386 GNU/Linux
 > 
 > 

Hmm, I haven't seen anything like that on my machine, a Pentium 4
running 2.6.12-1.1447_FC4.

Is there anything in particular you do to make it happen?  The
sytemtap script itself is pretty simple and doesn't do anything out of
the ordinary as far as I can tell.  I see _stp_map_del() in the trace
- is that always the case?

Tom




Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]