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

From: Arjan van de Ven
Date: Tue Oct 19 2010 - 09:28:06 EST


On 10/19/2010 4:52 AM, Ingo Molnar wrote:
* Peter Zijlstra<peterz@xxxxxxxxxxxxx> wrote:

On Tue, 2010-10-19 at 13:45 +0200, Ingo Molnar wrote:
* Thomas Renninger<trenn@xxxxxxx> 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

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