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Re: staprun -c deadlocks often


On Fri, Jun 17, 2011 at 02:43:13PM -0400, Frank Ch. Eigler wrote:
> rjones wrote:
> > [stap command prints the module name, used below]
> >   staprun -o /tmp/stap -c /bin/ls /home/rjones/.systemtap/cache/44/stap_44fe38ee6f62656645948ce5d275d678_260427.ko
> 
> Just running stap .... -c /bin/ls should give the same results.  Or
> are you cross-compiling?  (If so, there are other methods available
> that wouldn't require hand-copying and hand-running staprun.)

The reason I'm using staprun is to avoid recompiling the kernel module
each time.  I'm not sure how necessary this is, since I also noticed
that Systemtap seems to cache the module.  Will it always avoid
recompiling the exact same source?

Anyhow, in order to exclude staprun from the equation, I used just
stap:

sudo \
  stap \
    -o /tmp/stap \
    -c /bin/ls \
    -e 'probe module("ext2").statement ("*@*.c:*") { printf ("%s\n", pp()); }'

I get basically the same problem, although it appears to be slightly
less frequently (1 in 4?  1 in 5?) for some reason.

Process listing when it hangs:

29643 pts/5    Ss     0:00  \_ bash
29934 pts/5    S+     0:00  |   \_ sudo stap -o /tmp/stap -c /bin/ls -e probe mo
29935 pts/5    S+     0:00  |       \_ stap -o /tmp/stap -c /bin/ls -e probe mod
29936 pts/5    Sl+    0:00  |           \_ /usr/libexec/systemtap/stapio -o /tmp
29937 pts/5    S+     0:00  |               \_ /usr/libexec/systemtap/stapio -o


> > As I say, more often than half the time, instead of printing out a
> > directory listing, the staprun command will just hang.  [...]
> 
> This sounds like http://sourceware.org/PR10189, where too many warning
> messages interfere with non-warning staprun<->module packets.

It could be.  I'm still getting warning messages (see previous email).

Is there a way to get it to discard the warning messages?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org


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