Re: [RFC][PATCH 0/8] perf pmu interface

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2010-06-16 at 18:00 +0200, Peter Zijlstra wrote:
> These patches prepare the perf code for multiple pmus (no user
> interface yet, Lin Ming is working on that). These patches remove all
> weak functions and rework the struct pmu interface.
> 
> The latter is inspired by the work Frederic is doing to to filter out
> IRQ contexts.
> 
> These patches are very prelimenary, they haven't seen a compiler yet and
> the last patch still needs sparc,ppc and arm converted.
> 
> But they patches seem to be in a good enough shape to see what people
> think..

Another idea I was kicking about was to push find_get_context()
partially into struct pmu, so that we can have context's per pmu.

For cpu-wide contexts its easy, for per-task contexts we need more
pointers in task_struct, so I was thinking of something like:

enum {
  perf_swevent_context = 0,
  perf_cpu_context,
#ifdef HW_BREAKPOINT
  perf_bp_context,
#endif
  perf_nr_task_context
};

struct task_struct {
  ...
  struct perf_event_context *perf_event_ctxs[perf_nr_task_context];
  ...
};

and have add for loops over the struct pmu list for the cpu-wide
contexts and for loops over perf_nr_task_context for the task contexts.

It would add some extra code to the hot-paths, but its the best I can
come up with.