----- On Apr 19, 2016, at 1:13 PM, rostedt rostedt@xxxxxxxxxxx wrote: > On Tue, 19 Apr 2016 16:55:11 +0000 (UTC) > Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote: > >> ----- On Apr 19, 2016, at 10:34 AM, rostedt rostedt@xxxxxxxxxxx wrote: >> >> > From: Steven Rostedt <rostedt@xxxxxxxxxxx> >> > >> > Add the infrastructure needed to have the PIDs in set_event_pid to >> > automatically add PIDs of the children of the tasks that have their PIDs in >> > set_event_pid. This will also remove PIDs from set_event_pid when a task >> > exits >> > >> > This is implemented by adding hooks into the fork and exit tracepoints. On >> > fork, the PIDs are added to the list, and on exit, they are removed. >> > >> > Add a new option called event_fork that when set, PIDs in set_event_pid will >> > automatically get their children PIDs added when they fork, as well as any >> > task that exits will have its PID removed from set_event_pid. >> >> Just out of curiosity: how does it deal with multi-process and multi-thread ? >> What events are expected in each case ? >> > > Not sure what you mean by that. This is in-kernel, and it's simply > tasks. That is, any task (process or thread) that creates another task > has its kernel pid checked. That would be the thread ID as well. So it > works the same with processes as with threads because within the kernel > they are just all just "tasks". You register on sched_process_fork and sched_process_exit tracepoints for adding/removing PIDs to/from your "PID tracker". sched_process_fork() is called both when a process and when a thread is created. sched_process_exit() is called from do_exit(). Ah! and it seems do_exit is called whenever a user-space thread exits. The process exiting system call is rather exit_group(2). I was concerned that you might miss the thread exiting system calls, but it seems OK after digging back into that part of the kernel source code. It's been a while since last time I had to do modeling of the kernel state based on events by myself, sorry about the confusion. :-) Thanks, Mathieu > > -- Steve -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-trace-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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