Subject: [PATCH 4/6] perf-events: export enable/disable event symbols to kernel modules

From: [email-masked] (Will Deacon)
Date: Wed, 10 Mar 2010 14:41:41 -0000

Hi Peter,

> Ah, very nice. Can something like that be done in general, like an
> arch-independent oprofile backend using perf, or is there too much
> arch-specific bits to the oprofile stuff?

In theory, it should be possible but it would require that:

(a) all the architectures that have OProfile support have equivalent support in Perf
(b) the OProfile userspace tools would need tweaking so that the kernel interface:
    i.)  is identical across different architectures
    ii.) has a 1:1 mapping with perf. That is, OProfile tools must agree with perf
         on things like number of counters and PMU name [which I don't think the
         generic perf code needs to care about].

> I know Robert talked about doing something like this, I just have no
> clue how arch specific this would be.

I think it would be a nightmare to fix up all the edge-cases that each architecture
has at the moment. If, in the long run, each architecture ends up defining their own
oprofile <-> perf interface then it would make sense to look at merging them at the
higher level.

Will