On Wed, May 26, 2010 at 11:46 PM, Pierre-Marc Fournier <[email protected]> wrote: >> For large programs or programs that closely manage resources, a >> documented list of resources that libust uses would be useful. This >> information can be used to understand whether libust might interfere >> with the program being traced. For example, will heap allocations be >> made after startup? Will file descriptors be held open? The listener >> thread? > > Currently, ust is designed to be transparent to the running process in most > cases. However, if your program makes very unusual assumptions about the > usage of some resources, this could result in a conflict. > > - Yes, heap allocations can be made after startup. > - Sockets will definitely be kept open by the listener thread. > - Currently, I don't think any file descriptors are kept open, but it could > be the case in the future. > - SystemV shared memory segments are mapped in the address space. > - A listener thread is always started to wait for connections from ustctl or > ustd. > > If you feel it would be important to avoid some of these things, please let > me know.
Thanks for explaining, sounds fine to me. If you want to add this as an appendix to the documentation I think it is useful information for an application developer who wants to integrate UST support. >> I don't understand the --create-trace, --alloc-trace, --destroy-trace, >> and subbuf concepts that ustctl exposes. Perhaps these are documented >> in kernel LTTng and I haven't read that. > > Normally you should not need to go to LTTng kernel tracer documentation to > understand. > > I just pushed an updated manpage for ustctl in the git which clarifies these > concepts. If you think things could be even clearer, let me know. Great thanks, will check out the documentation. Stefan _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
