Messages in this thread | | | Subject | Re: [RFC][PATCH 0/4] tracing: Add event-fork to trace tasks children | From | Daniel Bristot de Oliveira <> | Date | Tue, 19 Apr 2016 23:05:28 -0300 |
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On 04/19/2016 11:34 AM, Steven Rostedt wrote: > This code adds the event-fork option that, when set, will have tasks > with their PIDs in set_event_pid add their children PIDs when they > fork. It will also remove their PID from the file on exit.
That is a nice feature! I tested it and it works. But, look this...
Set the event-fork, the current shell pid, and enable the trace:
[root@f23 tracing]# echo event-fork > trace_options [root@f23 tracing]# echo $$ > set_ftrace_pid [root@f23 tracing]# echo function > current_tracer
to exercise the feature, start the httpd...
[root@f23 tracing]# httpd
[root@f23 tracing]# cat trace | awk '{print $1}' | sort | uniq awk-2209 bash-2162 bash-2208 httpd-2196 httpd-2197 httpd-2199 httpd-2200 httpd-2201 httpd-2202 httpd-2203 httpd-2204 httpd-2205 httpd-2206 httpd-2207 sort-2210 uniq-2211
Awesome :-) it works!
But, the set_ftrace_pid only shows the pid of the shell. I thought it would print all child's pid.
[root@f23 tracing]# cat set_ftrace_pid 2162
Now, lets finish the session:
[root@f23 tracing]# echo 0 > tracing_on [root@f23 tracing]# echo nop > current_tracer [root@f23 tracing]# echo > trace [root@f23 tracing]# echo > set_ftrace_pid [root@f23 tracing]# echo noevent-fork > trace_options
and start a simple trace again, filtering the watchdog/0 thread:
[root@f23 tracing]# echo 14 > set_ftrace_pid [root@f23 tracing]# echo function > current_tracer [root@f23 tracing]# echo 1 > tracing_on
(this is a trick to make httpd work) [root@f23 tracing]# kill -1 2197
voilà!
[root@f23 tracing]# cat trace | awk '{print $1}' | sort | uniq httpd-2197 httpd-2501 httpd-2503 httpd-2506 httpd-2507 httpd-2526 httpd-2527 httpd-2528 httpd-2529 httpd-2530 httpd-2531 httpd-2532 httpd-2533 httpd-2534 httpd-2535 watchdog/0-14
The httpd stills being filtered, and I did not find a way to remove them. Although I see that they will be removed when they exit, I think it would be nice to remove them when cleaning set_ftrace_pid.
Am I missing something?
-- Daniel
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