From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning
Date: Mon, 12 Jan 2009 01:56:20 +0000
Message-ID: <20090112015620.GA6428@shareable.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Harvey Harrison <harvey.harrison@gmail.com>,
	Andi Kleen <andi@firstfloor.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>,
	Matthew Wilcox <matthew@wil.cx>,
	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>,
	Heiko Carstens <heiko.carstens@de.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar wrote:
> If it's used once in a single .c file it should be inlined even if
> it's large.

As Linus has pointed out, because of GCC not sharing stack among
different inlined functions, the above is surprisingly not true.

In kernel it's a problem due to raw stack usage.

In userspace apps (where stack used is larger), inlining single-call
functions could, paradoxically, run slower due to increased stack
dcache pressure for some larger functions.

-- Jamie