Hi, I've built with existing open source software a Linux DLM (Distributed Lock Manager) viewer [0]. The Linux DLM subsystem can be found in "fs/dlm" and its main users are gfs2, ocfs2 and cluster-md. It is like the name already propagates a distributed lock manager for Linux clusters. A cluster can have shared resources among several nodes. DLM offers to protect shared resources against mutual access e.g. cluster file system gfs2 which operates on shared block devices among several nodes. The viewer offers a graphical view about the used lock states over time in a cluster. Therefore we need to capture Linux DLM traces on all cluster nodes. This is done by using the trace-cmd record command with the time synchronization feature between multiple Linux machines which are part of the DLM cluster. Another tool is dlm2slog2 [1] reads the recorded Linux trace files, merges and converts them into a "drawable" open format known as "slog2" [2] by using the open slog2 sdk. The slog2sdk contains a viewer named "jumpshot" [3] which can be used to visualize the slog2 file. Originally this drawable format was invented to trace MPI (Message Passing Interface) applications, however it does not depend on MPI and offers a graphical tracing for distributed applications which I adapted for DLM lock states. The only "missing" piece here was the convert and merge of the recorded Linux traces to the slog2 fileformat. Hereby I would like to thank all trace-cmd developers (especially those who made the time synchronization feature) and slog2sdk developers which offered they work as open source so it was easy for me to make a small piece of software "dlm2slog2" that works as a bridge between trace-cmd/linux tracing and slog2sdk. As the slog2sdk is written in Java I did Java bindings similar to the existing python bindings for libtracecmd, similar classes, etc. underneath it uses swig. I would like to try to bring those bindings upstream to trace-cmd. It's _not_ necessary to have a Java dependency on trace-cmd, there should be some trace-cmd-java package available which installs the necessary swig library libctracecmdjava that offers jni access to libtracecmd. As well a jar file which can be seen as a library/python module and follows the same license as libtracecmd. The alternative here would be to maintain an out-of-tree trace-cmd-java package. I would like to hear some feedback for it, the current code can be found at [4]. If you want to get started or simply see what this is all about inclusive screenshots, see [0]. - Alex [0] https://gitlab.com/netcoder/dlm2slog2/-/wikis/home [1] https://gitlab.com/netcoder/dlm2slog2 [2] https://www.mcs.anl.gov/research/projects/perfvis/software/log_format/index.htm#SLOG-2 [3] https://www.mcs.anl.gov/research/projects/perfvis/software/viewers/index.htm#Jumpshot-4 [4] https://gitlab.com/netcoder/trace-cmd/-/commits/java_bindings
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