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From: Andrew Morton <akpm@linux-foundation.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	hugh@veritas.com, Linux Memory Management <linux-mm@kvack.org>
Subject: Re: [RFC/PATCH] prepare_unmapped_area
Date: Mon, 5 Feb 2007 22:54:18 -0800	[thread overview]
Message-ID: <20070205225418.b0eb0346.akpm@linux-foundation.org> (raw)
In-Reply-To: <20070206064034.GB5549@wotan.suse.de>

On Tue, 6 Feb 2007 07:40:34 +0100 Nick Piggin <npiggin@suse.de> wrote:

> On Mon, Feb 05, 2007 at 10:37:47PM -0800, Andrew Morton wrote:
> > On Tue, 6 Feb 2007 07:12:11 +0100 Nick Piggin <npiggin@suse.de> wrote:
> > > 
> > > It still costs a whole nother cacheline, for just an empty function on
> > > !hugepage kernels.
> > 
> > Doubtful, especially with CONFIG_CC_OPTIMIZE_FOR_SIZE=y.
> 
> Oh, does the function call get stripped out in that case? Why does it
> get left in with OPTIMIZE_FOR_SIZE=n, I wonder?

It's still there, but is probably sharing a cacheline with the callee,
assuming the linker leaves functions in the programmer-specfied order,
which it usually does.

Some of the fancy linker options might subvert that, dunno.

--
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  reply	other threads:[~2007-02-06  6:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <200702060405.l1645R7G009668@shell0.pdx.osdl.net>
     [not found] ` <1170736938.2620.213.camel@localhost.localdomain>
     [not found]   ` <20070206044516.GA16647@wotan.suse.de>
2007-02-06  5:04     ` [RFC/PATCH] prepare_unmapped_area Benjamin Herrenschmidt
2007-02-06  5:31       ` Andrew Morton
2007-02-06  5:46         ` Benjamin Herrenschmidt
2007-02-06  5:58           ` Andrew Morton
2007-02-06  6:02             ` Benjamin Herrenschmidt
2007-02-06  6:08               ` Andrew Morton
2007-02-06  6:12             ` Nick Piggin
2007-02-06  6:37               ` Andrew Morton
2007-02-06  6:40                 ` Nick Piggin
2007-02-06  6:54                   ` Andrew Morton [this message]
2007-02-06  9:55       ` Christoph Hellwig
2007-02-06 10:07         ` Benjamin Herrenschmidt
2007-02-06 10:23           ` Christoph Hellwig
2007-02-06 15:56       ` Adam Litke
2007-02-06 20:12         ` Benjamin Herrenschmidt
2007-02-06 20:52           ` Adam Litke
2007-02-06 21:02             ` Benjamin Herrenschmidt

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