Re: [PATCH v3 4/5] trace-cmd split: Enable support for buffer selection

Pierre Gondois <pierre.gondois@xxxxxxx> · Thu, 25 Jan 2024 16:16:42 +0100

Hello Steven,

On 1/24/24 23:37, Steven Rostedt wrote:

[ Replying to the correct version of the patch I tested ]

On Tue, 23 Jan 2024 14:42:14 +0100
Pierre Gondois <pierre.gondois@xxxxxxx> wrote:

The 'trace-cmd split' command conserves all buffers/instances
of the input .dat file. Add support to select the instances to
keep and to place as the top instance in an output .dat file.

Multiple .dat files can be generated with different combinations
of the instances to keep. The first instance in the command line
is selected as the top instance in an output .dat file.

For example, with a trace recorded with:
   $ trace-cmd record -e sched_wakeup -B switch_instance \
     -e sched_switch -B timer_instance -e timer

I tried this with a trace.dat file that has a instance called "tast" and it
didn't work. Note, the top instance had no data.

   $ trace-cmd split -i /work/traces/trace-tast.dat -o /tmp/trace-tast2.dat -B tast

With this command, the expected behaviour should be:
trace-tast2.dat:
- Contains all the instances of the input trace-tast.dat file
trace-tast.dat.1:
- Contains the tast instance only, as the top instance

If the 2 files don't match the above description, there is an issue.

---

Otherwise, I believe the command line should be parsed as:
1-
Select all the desired instances with -B or --top,
the first instance is placed as the top instance.
2-
When parsing a '-o', select all the previously selected instances and
put them in the output file.
3-
Start all over again from 1-. If there is no output file described
at the end of the command line, place the result in [input_file].dat.X

So placing the output file at the end of the command line is important
here. If you think the command line should be parsed another way, please
let me know,

   $ trace-cmd report /tmp/trace-tast2.dat
cpus=2
tast:        trace-cmd-3559  [001] 59413.154884: sched_waking:         comm=kworker/u4:2 pid=1324 prio=120 target_cpu=000
tast:        trace-cmd-3564  [000] 59413.154900: sched_switch:         trace-cmd:3564 [120] R ==> kworker/u4:2:1324 [120]
tast:        trace-cmd-3559  [001] 59413.154907: sched_switch:         trace-cmd:3559 [120] S ==> trace-cmd:3565 [120]
tast:     kworker/u4:2-1324  [000] 59413.154911: sched_waking:         comm=sshd pid=18725 prio=120 target_cpu=001
tast:     kworker/u4:2-1324  [000] 59413.154929: sched_switch:         kworker/u4:2:1324 [120] I ==> sshd:18725 [120]
tast:             sshd-18725 [000] 59413.155120: sched_waking:         comm=sslh-fork pid=18724 prio=120 target_cpu=001
tast:             sshd-18725 [000] 59413.155178: sched_waking:         comm=kworker/0:1 pid=815 prio=120 target_cpu=000
tast:             sshd-18725 [000] 59413.155189: sched_switch:         sshd:18725 [120] S ==> sslh-fork:18724 [120]
tast:        sslh-fork-18724 [000] 59413.155303: sched_switch:         sslh-fork:18724 [120] S ==> kworker/0:1:815 [120]

Still has "tast" as an instance and not the top.> 

-- Steve

Creating a test.dat file containing the top instance and
the switch_instance:
   $ trace-cmd split --top -B switch_instance -o test.dat

Creating a test.dat file containing the switch_instance as
the top instance, and the initial top instance as an instance
named 'old_top':
   $ trace-cmd split -B switch_instance --top=old_top -o test.dat

Splitting all instances in different .dat files:
   $ trace-cmd split --top -o top.dat -B switch_instance \
     -o switch.dat -B timer_instance -o timer.dat

To achieve this, new 'struct name_list', 'struct output_file_list'
structures are created, with associated functions.

Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
---

Regards,
Pierre