Re: [PATCH 4/4] perf tools: Add perf trace

[Ingo Molnar <mingo@elte.hu>]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> This adds perf trace into the set of perf tools. It is written to 
> fetch the tracepoints samples from perf events and display them, 
> according to the events informations given by the debugfs files 
> through the util/trace* tools.
> 
> It is a rough first shot and doesn't yet handle the cpu, 
> timestamps fields and some other things.
> 
> Example:
> 
> perf record -f -e workqueue:workqueue_execution:record -F 1 -a
> perf trace
> 
>        kblockd/0-236   [000]     0.000000: workqueue_execution: thread=:236 func=cfq_kick_queue+0x0
>      kondemand/0-360   [000]     0.000000: workqueue_execution: thread=:360 func=do_dbs_timer+0x0
>      kondemand/0-360   [000]     0.000000: workqueue_execution: thread=:360 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0
>      kondemand/1-361   [000]     0.000000: workqueue_execution: thread=:361 func=do_dbs_timer+0x0

Nice!

> Todo:
> 
> - A lot of things!

heh :-)

To help this move forward i've put the patches into 
tip:perfcounters/tracing. We might still rebase that branch, should 
it become necessary, before merging it into perfcounters/core - but 
it should give a first glimpse to people who want to try this.

A first bugreport:

took me some time to figure out that i need to pass in -R to create 
a trace.info. I think we want to share the namespace anyway - 
there's no real difference between perf.data and trace.info - both 
contain trace records.

once i added -R i ran into this problem:

# perf record -R -f -e workqueue:workqueue_execution:record -F 1 -a
^C
[ perf record: Captured and wrote 0.250 MB perf.data (~10928 samples) ]

aldebaran:/home/mingo/linux/linux/tools/perf> perf trace
  Fatal: bad op token )
version = 0.5

Some missing patch?

	Ingo