Without much fanfare systemtap 0.8 was released a little while ago. There is one little tidbit in the release notes that does warrent some excitement though:

User space probing is supported at a prototype level, for kernels built with the utrace patches.

So what does that mean? Take for example the para-callgraph.stp script:

$ stap para-callgraph.stp 'process("/bin/ls").function("*")' -c /bin/ls
0 ls(12631):->main argc=0x1 argv=0x7fff1ec3b038
276 ls(12631): ->human_options spec=0x0 opts=0x61a28c block_size=0x61a290
365 ls(12631): <-human_options return=0x0
496 ls(12631): ->clone_quoting_options o=0x0
657 ls(12631):  ->xmemdup p=0x61a600 s=0x28
815 ls(12631):   ->xmalloc n=0x28
908 ls(12631):   <-xmalloc return=0x1efe540
950 ls(12631):  <-xmemdup return=0x1efe540
990 ls(12631): <-clone_quoting_options return=0x1efe540
1030 ls(12631): ->get_quoting_style o=0x1efe540
[...]
650290 ls(12631):  <-print_current_files
650330 ls(12631): <-print_dir
650456 ls(12631): ->free_pending_ent p=0×1f02d90
650539 ls(12631): <-free_pending_ent
650660 ls(12631): ->close_stdout
650821 ls(12631):  ->close_stream stream=0×376db6c780
650966 ls(12631):  <-close_stream return=0×0
651082 ls(12631):  ->close_stream stream=0×376db6c860
651164 ls(12631):  <-close_stream return=0×0
651205 ls(12631): <-close_stdout

That is timestamp, process name, tid, function entry and function exit with parameters and return values. Currently it relies on having the debuginfo files available, so make sure you install the coreutils-debuginfo package (if you want to trace /bin/ls and friends). Systemtap 0.8 should be in a distro near you soon. Fedora 10 already has it.

Another nice thing added in Fedora 10 is oprofile-jit, which enhances the system profiler with java support (for runtimes supporting jvmti/jvmpi, gcj native code was obviously already supported), just add -agentlib:jvmti_oprofile to your java invocation, and then opreport can give you stuff like:

samples  %        linenr info                 image name   app name    symbol name
136220   20.3345  (no location information)   21010.jo     java        Interpreter
15176     2.2654  indexSet.cpp:528            libjvm.so    libjvm.so   IndexSetIterator::advance_and_next()
12273     1.8321  (no location information)   21010.jo     java        int[] java.math.BigInteger.montReduce(int[], int[], int, int)
11129     1.6613  (no location information)   21010.jo     java        int java.text.CollationElementIterator.next()
9932      1.4826  (no location information)   21010.jo     java        java.lang.String com.sun.javatest.finder.JavaCommentStream.readComment()~1
9731      1.4526  (no location information)   21010.jo     java        java.nio.charset.CoderResult sun.nio.cs.UTF_8$Decoder.decodeArrayLoop(java.nio.ByteBuffer, java.nio.CharBuffer)
9239      1.3792  reg_split.cpp:409           libjvm.so    libjvm.so   PhaseChaitin::Split(unsigned int)
8617      1.2863  ifg.cpp:464                 libjvm.so    libjvm.so   PhaseChaitin::build_ifg_physical(ResourceArea*)

Note how you can see the percentages of time spend in the interpreter, compiled methods, hotspot (and if I would have it enabled, libc, kernel, etc). The above is clearly a somewhat short run (of the jtreg crypto tests) and you can see that most of the time is spend in the Interpreter because the methods haven’t been compiled yet.

Paul wrote about “Fedora 10 around the corner!” and said something really nice:

Last, but certainly not least, I want to thank you, the reader, if I haven’t already. You’re part of our community too, and without you we would be diminished. Free software isn’t just about bits and bytes, it’s about people, about doing something real, something tangible, something lasting for your fellow human beings. And with your help, the Fedora Project has been able to lead in free software innovation for over five years and ten releases now. Each and every one of you — pat yourself on the back for a job well done.

Thanks Paul, very well said.

This post by Kirill Grouchnikov from Pushing Pixels made me sad:

Trust is hard to build and easy to destroy

Are we really doing that badly? Ever since the full GPL release by Sun of the reference implementation of Java as OpenJDK and the positive wave that IcedTea brought to unite the existing libre java communities pushing Java into the core of the various GNU/Linux distros, I feel like the sky is the limit. We as a community now have the full freedom to cooperate with each other in whatever way we like. But for some the feeling is still not there. Are we afraid to really define “Java the next generation”? It seems the code and the spirit is there. But there is a leadership trust issue. How do we fix that?