Re: PATCH [0/4] perf: clean-up of power events API

[Arjan van de Ven <arjan@linux.intel.com>]

  On 10/19/2010 4:52 AM, Ingo Molnar wrote:
> * Peter Zijlstra<peterz@infradead.org>  wrote:
>
>> On Tue, 2010-10-19 at 13:45 +0200, Ingo Molnar wrote:
>>> * Thomas Renninger<trenn@suse.de>  wrote:
>>>
>>>>> Most definitely. It's no accident that it took such a long time for this issue
>>>>> to be raised in the first place. It's a rare occurance -
>>>> Do you agree that this occurance happened now and these events should get cleaned
>>>> up before ARM and other archs make use of the broken interface?
>>>>
>>>> If not, discussing this further, is a big waste of time... and Jean would have to
>>>> try to adapt his ARM code on the broken ABI...
>>> The discussion seems to have died down somewhat. Please re-send to lkml the latest
>>> patches you have to remind everyone of the latest state of things - the merge window
>>> is getting near.
>>>
>>> My only compatibility/ABI point is basically that it shouldnt break _existing_
>>> tracepoints (and users thereof). If your latest bits meet that then it ought to be a
>>> good first step. You are free to (and encouraged to) introduce more complete sets of
>>> events.
>> Can we deprecate and eventually remove the old ones, or will we be forever obliged
>> to carry the old ones too?
> We most definitely want to deprecate and remove the old ones - but we want to give
> instrumentation software some migration time for that.
>
> Jean, Arjan, what would be a feasible and practical deprecation period for that? One
> kernel cycle?

more like a year

for some time software needs to support both, especially if popular 
distros stick to an older kernel like *cough* RHEL6