Re: [PATCH 1/1] rasd: Use perf_evlist__open() instead of open coded

[David Ahern <dsahern@gmail.com>]

On 10/14/14, 7:56 AM, Jiri Olsa wrote:
> I read the rasd sources and realized we could poke this
> from another angle..  AFAIU the work the rasd does is following:
>     - reads config file and opens configured tracepoints
>     - reads samples comming from those tracepoints and displays/writes
>       this data to the console/file
>     - is there more?
>
> If I'm not missing anything, this is quite usefull/common usage
> pattern which would deserve new perf command.
>
> I can see the analogy with ftrace debugfs interface
>    - choose/enable tracepoints
>    - cat .../tracing/trace-pipe
>
> and there could be '-d' for the command to act as daemon.

Yes, this parallels a new use case on my end. Right now I am running 
perf record ... | perf script. With the tracepoints and filters involved 
it is a LOT of typing - and still collects more than is needed (I don't 
need MMAP events for example, only COMM events). I am leaning towards a 
new perf sub-command but from my scheduling timehist and daemon commands 
I know there is a lot of overhead that goes with that. A perf library 
with a stable API would make this a lot easier. (AFAIK the python 
bindings do not currently support opening events, it is mainly an 
analysis option.)

David