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wizzywiz
*nix forums beginner
Joined: 02 Jul 2006
Posts: 12
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 Posted: Sun Jul 16, 2006 10:17 am Post subject:
Why would Suse, on opteron, miss 500 megs of RAM?
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Hello. I'm using Suse 9.3 and 10.0 in our lab, on a dual opteron
(248s) IBM Intellistation A Pro or on a Dell Precision 470 Workstation.
Regardless of how much RAM I put in the dual opteron (from 4 to 8
gigs), it does not see all of the RAM, even when I use IBM-branded RAM.
The free command shows .5 gig less than is installed. When the machine
boots it shows the count of ram, and gets up to the full installed
amount, and then drops back down half a gig, then boots. IBM support
has come out on multiple occasions and done diagnostics, and their
software shows the full installed amount is recognized. They always
make sure the BIOS is the latest. I have worked with Chip Merchants
tech support and run their downloadable Memory tester, and it shows the
memory being short .5 gigs too. But they sent me two separate kinds of
RAM, and we have IBM RAM, and no matter which I install 8 gigs of, I
get the same results with the tester and with the free command, but the
IBM diagnostics show the full memory.
On our Dells, running the same OS, with 4 gigs of RAM, the free command
shows the full amount of installed RAM.
Is anybody aware of any reason why Suse would show a half-gig less than
the RAM installed on just the IBM, or any further tests I can try? At
this point I don't know if all the RAM is being used but Suse doesn't
report it or reserves some of it on the IBM opteron macine, or if in
fact not all of the RAM is being utilized or seen on the opteron
machine. IBM techs, of course, run their diagnostics and tell me it's
fine. I've elevated it as many tiers in tech support as I can, and
never reached anyone that had any idea.
Thanks,
Jim |
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robert bowman
*nix forums beginner
Joined: 10 Jun 2006
Posts: 44
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| Posted: Sun Jul 16, 2006 3:12 pm Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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wizzywiz wrote:
| Quote: | Is anybody aware of any reason why Suse would show a half-gig less than
the RAM installed on just the IBM, or any further tests I can try?
|
Onboard video? One of my systems shows 128 mB less than the physical memory
after the video controller grabs its chunk. I believe even some cards will
hit on system memory if they are feeling deprived.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
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----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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Markus Kossmann
*nix forums addict
Joined: 26 Feb 2005
Posts: 62
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| Posted: Sun Jul 16, 2006 3:47 pm Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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wizzywiz wrote:
| Quote: | Hello. I'm using Suse 9.3 and 10.0 in our lab, on a dual opteron
(248s) IBM Intellistation A Pro or on a Dell Precision 470 Workstation.
Regardless of how much RAM I put in the dual opteron (from 4 to 8
gigs), it does not see all of the RAM, even when I use IBM-branded RAM.
The free command shows .5 gig less than is installed.
Well, you need some address space (typically 0.5 G) for your PCI cards |
within the first 4 Gigabytes. If there is no option in the BIOS to map that
RAM into the space over 4G that RAM ist lost. So check the BIOS options of
the IBM workstation. |
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General Schvantzkoph
*nix forums Guru
Joined: 20 Feb 2005
Posts: 425
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| Posted: Mon Jul 17, 2006 1:21 am Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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On Sun, 16 Jul 2006 03:17:07 -0700, wizzywiz wrote:
| Quote: | Hello. I'm using Suse 9.3 and 10.0 in our lab, on a dual opteron
(248s) IBM Intellistation A Pro or on a Dell Precision 470 Workstation.
Regardless of how much RAM I put in the dual opteron (from 4 to 8
gigs), it does not see all of the RAM, even when I use IBM-branded RAM.
The free command shows .5 gig less than is installed. When the machine
boots it shows the count of ram, and gets up to the full installed
amount, and then drops back down half a gig, then boots. IBM support
has come out on multiple occasions and done diagnostics, and their
software shows the full installed amount is recognized. They always
make sure the BIOS is the latest. I have worked with Chip Merchants
tech support and run their downloadable Memory tester, and it shows the
memory being short .5 gigs too. But they sent me two separate kinds of
RAM, and we have IBM RAM, and no matter which I install 8 gigs of, I
get the same results with the tester and with the free command, but the
IBM diagnostics show the full memory.
On our Dells, running the same OS, with 4 gigs of RAM, the free command
shows the full amount of installed RAM.
Is anybody aware of any reason why Suse would show a half-gig less than
the RAM installed on just the IBM, or any further tests I can try? At
this point I don't know if all the RAM is being used but Suse doesn't
report it or reserves some of it on the IBM opteron macine, or if in
fact not all of the RAM is being utilized or seen on the opteron
machine. IBM techs, of course, run their diagnostics and tell me it's
fine. I've elevated it as many tiers in tech support as I can, and
never reached anyone that had any idea.
Thanks,
Jim
|
Check your BIOS to see if there is a feature called Memory Hole Remapping.
Traditionally the IOMMU has been mapped into the top of the 4G memory
space. This didn't matter when there was less than 4G of RAM but it
matters now. Memory Hole Remapping puts the IOMMU and the RAM into
different spaces so that the OS can see all of the RAM. You'll also need a
2.6.15 or higher kernel. The 2.6.14 kernel has a bug in the IOMMU code
which was fixed in 2.6.15.
I'm surprised that an Opteron system doesn't always do memory hole
remapping because servers have had more than 4G of RAM for a while now. |
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chuck@nil.car
*nix forums Guru Wannabe
Joined: 23 Aug 2005
Posts: 100
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| Posted: Mon Jul 17, 2006 11:47 pm Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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bowman <bowman@montana.com> wrote in news:1153062159_21906@corp.com:
| Quote: | wizzywiz wrote:
Is anybody aware of any reason why Suse would show a half-gig less
than the RAM installed on just the IBM, or any further tests I can
try?
Onboard video? One of my systems shows 128 mB less than the physical
memory after the video controller grabs its chunk. I believe even some
cards will hit on system memory if they are feeling deprived.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet
News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the
World! 120,000+ Newsgroups ----= East and West-Coast Server Farms -
Total Privacy via Encryption =----
|
500Meg for a video card? hardly likely.
--
(setq (chuck nil) car(chuck) ) |
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robert bowman
*nix forums beginner
Joined: 10 Jun 2006
Posts: 44
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| Posted: Tue Jul 18, 2006 2:13 am Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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chuckcar wrote:
| Quote: | 500Meg for a video card? hardly likely.
|
What rock have you been hiding under? Probably not on the OP's system but
512 mB video cards have been around for a while. Whatcha need is a handful
of eVGA 512-P2-N570-AX Geforce 7900GTX 512MB cards and a SLI mobo...
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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General Schvantzkoph
*nix forums Guru
Joined: 20 Feb 2005
Posts: 425
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| Posted: Tue Jul 18, 2006 11:03 am Post subject:
Re: Why would Suse, on opteron, miss 500 megs of RAM?
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On Mon, 17 Jul 2006 20:13:44 -0600, bowman wrote:
| Quote: | chuckcar wrote:
500Meg for a video card? hardly likely.
What rock have you been hiding under? Probably not on the OP's system but
512 mB video cards have been around for a while. Whatcha need is a handful
of eVGA 512-P2-N570-AX Geforce 7900GTX 512MB cards and a SLI mobo...
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
|
Your video card has it's own RAM, it doesn't use any of the main memory.
It's only the lowest end graphics systems that use main memory and those
systems use much less than 500Mbytes. However if any of you had bothered
to read my other post on this thread you would see that the OP's problem
has nothing to do with graphics. The problem is that the IO space is
mapped into the top of the first 4G of physical memory space. This is the
way it's always been done on PCs. There should be a feature in the BIOS
called Memory Hole remapping which move the IO space out of the way of the
RAM. I have a 4G X2 4400+ system, with Memory Hole Remapping off the BIOS
and Linux only see 3.5G, with Memory Hole Remapping on the BIOS and Linux
see all 4G. |
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