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From: Ingo Molnar <mingo@elte.hu>
To: Hugh Dickins <hugh@veritas.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [3/5] Mark complex bitops.h inlines as __always_inline
Date: Wed, 7 Jan 2009 14:18:46 +0100	[thread overview]
Message-ID: <20090107131846.GF3529@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0901061847110.29408@blonde.anvils>


* Hugh Dickins <hugh@veritas.com> wrote:

> Hugh Dickins noticed that released gcc versions building the kernel with 
> CONFIG_OPTIMIZE_INLINING=y don't inline some of the bitops - sometimes 
> generating very inefficient pageflag tests, and many instances of 
> constant_test_bit().

Could you quantify that please?

We really dont want to reintroduce __always_inline just for performance / 
code size reasons. If GCC messes up and makes a larger / more inefficient 
kernel, GCC will be fixed. CONFIG_OPTIMIZE_INLINING is default-off, so 
enable it only if it improves your kernel.

	Ingo

  reply	other threads:[~2009-01-07 13:19 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-04 23:36 [PATCH] [0/5] Couple of x86 patches for 2.6.29 Andi Kleen
2009-01-04 23:36 ` [PATCH] [1/5] Only scan the root bus in early PCI quirks Andi Kleen
2009-01-04 23:51   ` Yinghai Lu
2009-01-05  1:46     ` Andi Kleen
2009-01-04 23:36 ` [PATCH] [2/5] Allow HPET force enable on ICH10 HPET Andi Kleen
2009-01-04 23:36 ` [PATCH] [3/5] Mark complex bitops.h inlines as __always_inline Andi Kleen
2009-01-06  0:03   ` Andrew Morton
2009-01-06 10:17   ` Ingo Molnar
2009-01-06 14:32     ` Andi Kleen
2009-01-07 13:26       ` Ingo Molnar
2009-01-07 19:46         ` Andi Kleen
2009-01-06 19:17   ` Hugh Dickins
2009-01-07 13:18     ` Ingo Molnar [this message]
2009-01-08  2:16       ` Hugh Dickins
2009-01-08  5:07         ` Andi Kleen
2009-01-08  8:04       ` H. Peter Anvin
2009-01-04 23:36 ` [PATCH] [4/5] Use asm stubs for 32bit sigreturn codes Andi Kleen
2009-01-05  0:08   ` H. Peter Anvin
2009-01-04 23:36 ` [PATCH] [5/5] Avoid theoretical vmalloc fault loop Andi Kleen
2009-01-05 11:47   ` Nick Piggin

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