Re: [PATCH 6/8] rbtree: Implement generic latch_tree

From: Peter Zijlstra
Date: Thu Mar 19 2015 - 18:04:44 EST

On Thu, Mar 19, 2015 at 01:58:33PM -0700, Andrew Morton wrote:
> OK. This code is basically required to support perf/ftrace and
> modules, yes? Presumably small and space-constrained systems aren't
> using either, so they don't take the hit.
> However CONFIG_MODULES systems which aren't using perf/ftrace _do_ take
> a hit. How many systems are we talking here? All non-x86?

No, there's plenty !x86 systems that have NMI and perf/ftrace, in fact,
ARM has them (FIQ) and there's event some ARM chips that use them for
perf (i.MX6 is one).

But sure, we could make this depend on CONFIG_PERF_EVENTS ||
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