Re: [PATCH v3 5/5] perf/sdt: Add support to perf record to trace SDT events

From: Hemant Kumar
Date: Thu Oct 23 2014 - 01:31:43 EST



On 10/22/2014 03:11 PM, Masami Hiramatsu wrote:
(2014/10/22 17:20), Hemant Kumar wrote:
From "file_sdt_ent" we will find out the file name.
Convert this sdt note into a perf event and then write this into uprobe_events
file to be able to record the event.
Then, corresponding entries are added to uprobe_events file for
the SDT events.
After recording is done, these events are silently deleted from uprobe_events
file. The uprobe_events file is present in debugfs/tracing directory.

To support the addition and deletion of SDT events to/from uprobe_events
file, a record_sdt struct is maintained which has the event data.
OK, I have some comments on this.

An example usage:

# ./perf record -e %user_app:fun_start -aR /home/user_app
At first, I'd like to add SDT support for adding probes too, like below;

./perf probe -a '%user_app:fun_start $vars'
But I think, previously we discussed that we won't be having "perf
probe" for SDT events.
We list them and probe/trace them using "perf record" directly.
Right, sorry for confusing you. I meant that I'd like to support SDT on both of
perf-record and perf-probe :)

I plan to do this and add this subsequently but will it be okay if we go with the current
implementation for the time being?

What do you think?

And even if we'll hide sdt related events via perf, users can access it via ftrace.
So, I doubt that we can completely hide them, in that case, honesty is the best way;)

Thank you,



--
Thanks,
Hemant Kumar

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