Message-ID: <4B511B12.6010208@zytor.com>
Date: Fri, 15 Jan 2010 17:49:06 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Yuhong Bao <yuhongbao_386@hotmail.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>, mingo@redhat.com,
        linux-kernel@vger.kernel.org
Subject: Re: Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks
References: <SNT125-W41CEF6892DBE0B1FD99B4AC3780@phx.gbl>
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On 12/30/2009 05:29 PM, Yuhong Bao wrote:
> 
> Given that Linus was once talking about the performance penalties of PAE and HIGHMEM64G, perhaps you'd find these benchmarks done by Phoronix of interest:
> http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae
> 

The big difference isn't between HIGHMEM4G (no PAE) and HIGHMEM64G
(PAE), it's between HIGHMEM and !HIGHMEM.  That cutoff is ~892 MB for a
stock 32-bit kernel.

	-hpa
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