Date: Fri, 9 Jan 2009 19:02:13 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Dirk Hohndel <hohndel@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>, Matthew Wilcox <matthew@wil.cx>,
       "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
       jim owens <jowens@hp.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       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
Subject: Re: [patch] measurements, numbers about CONFIG_OPTIMIZE_INLINING=y impact
Message-ID: <20090109180213.GH26290@one.firstfloor.org>
References: <alpine.LFD.2.00.0901081943150.6528@localhost.localdomain> <20090109130057.GA31845@elte.hu> <49675920.4050205@hp.com> <20090109153508.GA4671@elte.hu> <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>
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> I think that's the point. gcc will not get it right. 

I don't think that's necessary an universal truth. It 
can be probably fixed.

> So we need to do it ourselves in the kernel sources.
> We may not like it, but it's the only way to guarantee reproducable
> reliable inline / noinline decisions.

For most things we don't really need it to be reproducable,
the main exception are the inlines in headers.

Universal noinline would also be a bad idea because of its
costs (4.1% text size increase). Perhaps should make it
a CONFIG option for debugging though.

-Andi


> 
> /D
> 
> -- 
> Dirk Hohndel
> Intel Open Source Technology Center
> 

-- 
ak@linux.intel.com
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