Re: [RFC PATCH 0/4] perf: Custom contexts

From: Frederic Weisbecker
Date: Wed Mar 16 2011 - 09:53:34 EST

On Tue, Mar 15, 2011 at 11:32:54PM +0100, Peter Zijlstra wrote:
> Right, so I don't much like the interface, two new ioctl()s and a flag
> of dubious use.

Do you think we need a new syscall for this new feature.

> How important is this recursive nature of the thing to you:
> > It's supposed to support infinite combinations with starter having starters
> > themselves, plus filters, etc...
> We've so far avoided recursion like that, we only have single level
> groups etc.

There is actually no recursivity of any sort that the kernel has to handle.
The starter/stopper links are never handled recursively. ie: there is no
loop walking through the entire chain of starter to starter to starter, etc...

It's always only handled between direct related event: starter and target, but
never further.

Only the final effect has recursion properties in the resulting count
or trace.
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