Again along the lines of perfecting the display of processes states from kernel
traces, I have another small suggestion. The code needed to convert event data
to "state" information is simple and well localized. It is therefore fairly
easy to leverage the infrastructure put in place by the TMF team to refine the
control flow view display. As an example, my suggested improvement makes a
noticeable change yet the patch is a one liner! If you have suggestions and
ideas, we will be most interested in discussing possible further improvements.
I am tracing a shell script which does among other things "sleep 1; myprog". In
the control flow view, we see the new process, for example 10192, called sh
waiting for 1 second and then, on another line, a process named sleep with the
same pid (10192) which comes out of waiting and terminates (lasting only a few
miliseconds). This is rather counter-intuitive as sleep is not doing the sleep
part. This is explained by the fact that the command name is taken from the
sched_switch event. TMF thus only sees the new name long after the execve, when
coming back from waiting; it then starts a new line for that process with the
same pid but a new name.
One possibility is to change the name at the execve. However, the execve event
contains the file name but not the (sometimes different) command name. My
proposed change is to update the name at each sched_switch, thus in practice
retaining the last command name seen for the process. Update means change the
value for the whole interval, instead of Modify which keeps the old value up to
now and changes for the new value after now. This one line change is provided
at the message end.
Another possibility is to "modify" the name at each execve, using the "file
name" which may differ from the command name, and to "update" with the correct
command name at later sched_switch events. This would put on a separate line in
the control flow view each different program executed, even if they are the
same process.
diff --git
a/lttng/org.eclipse.linuxtools.lttng2.kernel.core/src/org/eclipse/linuxtools/internal/lttng2/kernel/core/stateprovider/CtfKernelStateInput.java
b/lttng/org.eclipse.linuxtools.lttng2.kernel.core/src/org/eclipse/linuxtools/internal/lttng2/kernel/core/stateprovider/CtfKernelStateInput.java
index 2d48bbb..4e1d422 100644
---
a/lttng/org.eclipse.linuxtools.lttng2.kernel.core/src/org/eclipse/linuxtools/internal/lttng2/kernel/core/stateprovider/CtfKernelStateInput.java
+++
b/lttng/org.eclipse.linuxtools.lttng2.kernel.core/src/org/eclipse/linuxtools/internal/lttng2/kernel/core/stateprovider/CtfKernelStateInput.java
@@ -242,7 +247,7 @@ public class CtfKernelStateInput extends
AbstractStateChangeInput {
/* Set the exec name of the new process */
quark = ss.getQuarkRelativeAndAdd(newCurrentThreadNode,
Attributes.EXEC_NAME);
value = TmfStateValue.newValueString(nextProcessName);
- ss.modifyAttribute(ts, value, quark);
+ ss.updateOngoingState(value, quark);
/*
* Check if we need to set the syscall state and the PPID of
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