DTrace Hangout Notes 02 Feb 2017
- gnn@ to create a mailing list associated with OpenDTrace
- gnn@ has finished
markj@ has put a change to USDT relocations (https://reviews.freebsd.org/D9374) that addresses the use of undefined behavior in the linker. rwatson@ points out that there are several folks on the project with linker experience at the moment.
- domagoj@ has looked into how to better integrate his virtual machine RFD with the work being done by Graeme on CADETS. domagoj@ would like to eliminate the need for zookeeper to identify the nodes. rwatson@ says that we are more interested in getting the distributed DTrace thing correct. For the purposes of hypervisors rwatson@ does not think we should not converge these two things but take advantage of the fact that hypervisors do not have the communication issues that networked systems do.
- There remains the question of where to keep the probe list, in the kernel or in user space. Domagoj suggests that it can remain in the kernel in a matrix. rwatson@ suggests that we experiment with the simplest possible system and that points us back towards the kernel.
- James asks about updating scripts on the fly. rwatson@ says that this is done in the DDTrace system by updating the DIF on the fly. The question is bast asked of Graeme.
- gnn@ says he'll be submitting RFDs for if() and do/while().
- gnn@ has imported the lastest xnu and macos-dtrace tarballs into the opendtrace repos
- shrikanth@ wants to talk about CTF sections becoming huge when dealing with more embedded systems. shrikanth@ and the Juniper folks are looking at being able to load the CTF sections on demand. markj@ says that this should be doable with libproc but that this has not yet been MFC'd to STABLE/11. James says that they'd like to move to DWARF since all their other tools are DWARF but that has only been a prototype. There is a CTF compressed flag but no one knows is the sections are actually compressed or not.
- rwatson@ mentions that emaste@ is working on libelf like things and gnn@ will talk to him about CTF features in that arena
- Domgaoj asks about having anonymous tracing switch to using a file once we've gone multi-user. markj@ thinks we'll need a filesystem to make this all work so there is a question of where to switch over.
- We'd like to bring over the stack tracing for Python. Isilon does have patches for this, but they're invasive.
- gnn@ will ask Graeme about the patches to libdtrace that might still be outstanding.
- Damogoj is looking at instance local variables.
- Those with access to Phabricator should join the DTrace group therein