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Systemtap + tracing processes inside a qemu guest
- From: "Richard W.M. Jones" <rjones at redhat dot com>
- To: systemtap at sources dot redhat dot com
- Date: Mon, 10 Oct 2011 10:10:26 +0100
- Subject: Systemtap + tracing processes inside a qemu guest
I have a program (libguestfs) where the architecture is something
like this:
+--------------+ +----------------------------+
| program on | | +-----------------+ |
| host <--------------> daemon in guest | |
| | socket | +-----------------+ |
+--------------+ | qemu |
+----------------------------+
I've instrumented the host program with DTRACE macros according to [1]
and that works well. However to get the complete picture I'd like to
instrument the daemon too. The aim would be to get timing information
across both the host program and the daemon:
0.001s program event #1 send message
0.005s daemon event #1 receive message
0.010s daemon event #2 send reply
0.025s program event #2 receive reply
(Note: I'm not interested in the qemu process itself, only in kernel +
userspace programs running inside the qemu virtual machine.)
What's possible at the moment?
I've read 'stapsh.c' and bug 13078 [2]. I'm not clear how to put it
all together, or even if this is possible right now.
Rich.
[1] http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps
[2] http://sourceware.org/bugzilla/show_bug.cgi?id=13078
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/