From: Matt Domsch <Matt_Domsch@dell.com>
To: "Martin J. Bligh" <mbligh@aracnet.com>
Cc: Sean Neakums <sneakums@zork.net>, Nagy Tibor <nagyt@otpbank.hu>,
xela@slit.de, mochel@osdl.org, bmoyle@mvista.com,
orc@pell.chi.il.us, linux-kernel@vger.kernel.org
Subject: Re: HIGHMEM
Date: Fri, 13 Feb 2004 16:09:09 -0600 [thread overview]
Message-ID: <20040213160909.A6102@lists.us.dell.com> (raw)
In-Reply-To: <64200000.1076688313@[10.10.2.4]>; from mbligh@aracnet.com on Fri, Feb 13, 2004 at 08:05:14AM -0800
On Fri, Feb 13, 2004 at 08:05:14AM -0800, Martin J. Bligh wrote:
> >> We have two Dell Poweredge servers, an older one (PowerEdge 6300) and a
> >> newer one (PowerEdge 6400). Both servers have 4GB RAM, but the Linux
> >> kernel uses about 500MB less memory in the newer machine.
> >
> > I may be talking through my hat, but I think that in this case you
> > need to select the option for support of 64G highmem. If I recall,
> > "4G highmem" refers not to the total amount to the memory, but to the
> > highest physical address that can be accessed.
>
> That's exactly correct. Whether the gain of 500MB of RAM is worth the
> overhead of PAE is another question ... but that's how to do it ;-)
If the chipset and BIOS can't remap the physical RAM out of the
address space needed by the PCI devices and into PAE space, then PAE
doesn't buy you anything. You need chipset support for RAM remapping,
which doesn't exist on the servers mentioned.
Thanks,
Matt
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
next prev parent reply other threads:[~2004-02-13 22:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-13 12:20 HIGHMEM Nagy Tibor
2004-02-13 13:12 ` HIGHMEM Sean Neakums
2004-02-13 16:05 ` HIGHMEM Martin J. Bligh
2004-02-13 22:09 ` Matt Domsch [this message]
2004-02-13 22:18 ` HIGHMEM Martin J. Bligh
2004-02-13 17:08 ` HIGHMEM david parsons
2004-02-13 13:36 ` HIGHMEM Matt Domsch
-- strict thread matches above, loose matches on Subject: below --
2003-04-15 14:39 HIGHMEM Nagy Tibor
2003-04-15 15:14 ` HIGHMEM William Lee Irwin III
2003-04-15 16:03 ` HIGHMEM Samuel Flory
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