From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <andi@firstfloor.org>
Subject: Re: [patch] measurements, numbers about CONFIG_OPTIMIZE_INLINING=y impact
Date: Fri, 9 Jan 2009 20:35:06 +0100
Message-ID: <20090109193506.GL26290@one.firstfloor.org>
References: <49677CB1.3030701@zytor.com> <20090109084620.3c711aad@infradead.org> <20090109172011.GD26290@one.firstfloor.org> <20090109172801.GC6936@parisc-linux.org> <20090109174719.GG26290@one.firstfloor.org> <20090109094142.367012b6@infradead.org> <20090109180213.GH26290@one.firstfloor.org> <alpine.LFD.2.00.0901090954410.6528@localhost.localdomain> <20090109185509.GJ26290@one.firstfloor.org> <alpine.LFD.2.00.0901091045090.6528@localhost.localdomain>
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Cc: Andi Kleen <andi@firstfloor.org>,
	Dirk Hohndel <hohndel@infradead.org>,
	Matthew Wilcox <matthew@wil.cx>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	jim owens <jowens@hp.com>,
	Chris Mason <chris.mason@oracle.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	paulmck@linux.vnet.ibm.com, Gregory Haskins <ghaskins@novell.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-btrfs <linux-btrfs@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Piggin <npiggin@suse.de>,
	Peter Morreale <pmorreale@novell.com>,
	Sven Dietrich <SDietrich@novell.com>, jh@suse.cz
To: Linus Torvalds <torvalds@linux-foundation.org>
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List-ID: <linux-btrfs.vger.kernel.org>

> What happens when you say -fno-inline-functions-called-once? Does it 
> disable inlining for those functions IN GENERAL, or just for the LARGE 

It does disable it in general, unless they're marked inline explicitely :

The traditional gcc 2.x rules were:

I Only inline what is marked inline (but it can decide to
not inline)
II Also inline others heuristically only with 
-O3 / -finline-functions [which we don't set in the kernel]

Then at some point this additional rule was added:

- Also inline everything static that is only called once
[on the theory that this shrinks code size which is true
according to my measurements]

-fno-inline-functions-called once disables this new rule.
It's very well and clearly defined.

-Andi

-- 
ak@linux.intel.com