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Date: Thu, 26 Oct 2017 20:10:36 +1100
From: "Tobin C. Harding" <>
To: Greg KH <>
Cc: "Jason A. Donenfeld" <>,, Theodore Ts'o <>,
	Linus Torvalds <>,
	Kees Cook <>,
	Paolo Bonzini <>,
	Tycho Andersen <>,
	"Roberts, William C" <>,
	Tejun Heo <>,
	Jordan Glover <>,
	Petr Mladek <>, Joe Perches <>,
	Ian Campbell <>,
	Sergey Senozhatsky <>,
	Catalin Marinas <>,
	Will Deacon <>,
	Steven Rostedt <>,
	Chris Fries <>, Dave Weinstein <>,
	Daniel Micay <>,
	Djalal Harouni <>,
	LKML <>
Subject: Re: [PATCH v7] printk: hash addresses printed with %p

On Thu, Oct 26, 2017 at 09:00:03AM +0200, Greg KH wrote:
> On Thu, Oct 26, 2017 at 12:59:08AM +0200, Jason A. Donenfeld wrote:
> > On Thu, Oct 26, 2017 at 12:27 AM, Tobin C. Harding <> wrote:
> > > How good is unlikely()?
> > 
> > It places that branch way at the bottom of the function so that it's
> > less likely to pollute the icache.
> But always measure it.  Lots of times (old numbers were 90% or so), we
> get the marking wrong, so please, always benchmark the thing to verify
> it actually is doing what you think it should be doing, otherwise it
> could make the code worse.

Does this come under 'premature optimization is the root of all evil'?

Should we be leaving out things like unlikely() and __read_only until
the code has been profiled?


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