linux-kernel - Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page optionally

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Message-ID: <20110128073909.GC15569@one.firstfloor.org>
Date:	Fri, 28 Jan 2011 08:39:09 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Huang Ying <ying.huang@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Avi Kivity <avi@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"Luck, Tony" <tony.luck@...el.com>,
	Dean Nelson <dnelson@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page optionally

> > Also longer term we'll get compilers that can do cross-file inlining
> > for optimized builds.
> 
> Which we'll probably need to turn off all over the place :(

Why? 

> 
> > So please better avoid these kinds of micro optimizations unless
> > it's a really really extremly speed critical path.
> 
> It's not just speed and it's not just .text size, either. Calling a
> ten-arg function consumes stack space.

gcc is pretty good at handling tail calls. Take a look at the code
it generates.


-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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