Re: [PATCH 2/2] perf: Userspace software event and ioctl

* Pawel Moll [off-list ref] wrote:

On Fri, 2014-09-26 at 12:23 +0100, Ingo Molnar wrote:

quoted

quoted

As in: allows *all* tasks to inject the data? Are you sure we 
don't want more fine-grained control, in particular per task?

Yeah. If the profiler allows it, then any task that is being 
traced can inject data.

The "that is being traced" fragment was the key here. I missed 
the fact that perf trace already takes a list of pids, so we're 
not talking about all tasks in the system. That should work.

Yeah, when we generate a user trace event, we should look at the 
currently active perf context's (percpu ones plus task ones), and 
inject into those only.

This way we limit event generation to those buffers that are 
actively interested in this task.

Thanks,

	Ingo