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

From: David Ahern
Date: Tue Oct 14 2014 - 10:19:59 EST

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.)


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