linux-kernel - Re: [PATCH 00/10] jump label: introduce very

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Message-ID: <20120222155110.GB28314@elte.hu>
Date:	Wed, 22 Feb 2012 16:51:10 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Jason Baron <jbaron@...hat.com>, a.p.zijlstra@...llo.nl,
	mathieu.desnoyers@...icios.com, davem@...emloft.net,
	ddaney.cavm@...il.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 00/10] jump label: introduce very_[un]likely + cleanups +
 docs


* H. Peter Anvin <hpa@...or.com> wrote:

> On 02/22/2012 12:18 AM, Ingo Molnar wrote:
> > 
> > For example could you tell *at a glance* what this does:
> > 
> > +       if (!static_branch_def_false(&perf_sched_events.key))
> > 
> > ?
> 
> Yes. [...]

You have specially built eyes I guess - congrats, you are member 
of the 1% :-)

> [...]  Unlike
> 
> > +       if (very_unlikely(&perf_sched_events.key))
> 
> ... which is actively misleading.

Misleading in what way? It clearly conveys that the slowpath 
that follows is a slowpath, that what follows is 'very 
unlikely'.

This is how all current kernel code is using these facilities.

If you have a new usecase (CPU feature flags) then you should 
outline that, instead of expecting something of current usecases 
that they are clearly not ...

Thanks,

	Ingo
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