I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of RAM.
$ uname -a Linux localhost.localdomain 2.6.26.3-14.fc8 #1 SMP Wed Sep 3 03:40:05 EDT 2008 i686 i686 i386 GNU/Linux
Even though I have 4GB of RAM installed, Linux appears to only be using 3GB of it.
$ free -t total used free shared buffers cached Mem: 3106944 777056 2329888 0 60608 419608 -/+ buffers/cache: 296840 2810104 Swap: 2040244 0 2040244 Total: 5147188 777056 4370132
I've read in other posts to this group that the cause of this is that the BIOS remaps the some (1GB) of memory to serve as address space for PCI devices, thus creating a memory "hole".
I understand that some BIOSes allow one to remap those devices elsewhere in the map. My BIOS does NOT allow that option.
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Thanks
On Wed, 2008-10-01 at 08:54 -0400, Linuxguy123 wrote:
I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of RAM.
$ uname -a Linux localhost.localdomain 2.6.26.3-14.fc8 #1 SMP Wed Sep 3 03:40:05 EDT 2008 i686 i686 i386 GNU/Linux
Even though I have 4GB of RAM installed, Linux appears to only be using 3GB of it.
$ free -t total used free shared buffers cached Mem: 3106944 777056 2329888 0 60608 419608 -/+ buffers/cache: 296840 2810104 Swap: 2040244 0 2040244 Total: 5147188 777056 4370132
I've read in other posts to this group that the cause of this is that the BIOS remaps the some (1GB) of memory to serve as address space for PCI devices, thus creating a memory "hole".
I understand that some BIOSes allow one to remap those devices elsewhere in the map. My BIOS does NOT allow that option.
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Overall, the issue is that you are running a 32-bit version of Linux. In order to take advantage of the entire 4GB you need to either:
1) Run a 64-bit version
2) Run the 32-bit PAE kernel (PAE stands for Physical Address Extensions)
At this point, it's preferable (IMHO) to just run the 64-bit version if you can stand to re-install. You will get better results overall in terms of performance compared to the PAE kernel and most all of the issues around 32-bit / 64-bit compatibility have been resolved or worked around. See the F9 release notes for details on these.
...and yes, this also applies to Windows systems. You have to run 64-bit versions of Windows XP or Vista to see the full 4GB as well.
Cheers,
Chris
-- ================================== By all means marry; If you get a good wife, you'll be happy. If you get a bad one, you'll become a philosopher.
--Socrates
On Wed, 01 Oct 2008 08:54:51 -0400 Linuxguy123 linuxguy123@gmail.com wrote:
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
You're complicating this way more than it needs to be. Try either the PAE kernel, or Fedora x86_64. I have set up several computers that require one or the other to see 4gb of ram.
On Wed, Oct 1, 2008 at 7:54 AM, Linuxguy123 linuxguy123@gmail.com wrote:
[SNIP]
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Thanks
Maybe someone can word this better than I but here it goes. The memory limit is not really tied to the OS "TYPE" (i.e. Windows XP/Vista, Linux, etc) but more to the architecture (32-bit vs. 64-bit). As far as I'm aware, all 32-bit OS's will have this limitation and all 64-bit OS's will not. You can get Windows XP, Vista or Linux in both 32 and 64-bit flavors.
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Richard
On Wed, 2008-10-01 at 11:17 -0500, Richard Shaw wrote:
Maybe someone can word this better than I but here it goes. The memory limit is not really tied to the OS "TYPE" (i.e. Windows XP/Vista, Linux, etc) but more to the architecture (32-bit vs. 64-bit). As far as I'm aware, all 32-bit OS's will have this limitation and all 64-bit OS's will not. You can get Windows XP, Vista or Linux in both 32 and 64-bit flavors.
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
i don't know the guts of fedora/rh... but i would imagine that a chunk of the mem space is reserved for system operational functions. as a result, the mem space that you, the app has, is the mem that's left over for apps to play in..
the reserved mem space might be used for swap, mem checking, error checking, os kernel functions, etc...
-----Original Message----- From: fedora-list-bounces@redhat.com [mailto:fedora-list-bounces@redhat.com]On Behalf Of Mike Chambers Sent: Wednesday, October 01, 2008 9:33 AM To: Community assistance, encouragement,and advice for using Fedora. Subject: Re: Using all of 4GB RAM... questions and Vista versus Linux...
On Wed, 2008-10-01 at 11:17 -0500, Richard Shaw wrote:
Maybe someone can word this better than I but here it goes. The memory limit is not really tied to the OS "TYPE" (i.e. Windows XP/Vista, Linux, etc) but more to the architecture (32-bit vs. 64-bit). As far as I'm aware, all 32-bit OS's will have this limitation and all 64-bit OS's will not. You can get Windows XP, Vista or Linux in both 32 and 64-bit flavors.
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
-- Mike Chambers Fedora Project - Ambassador, Bug Zapper, Tester, User, etc.. mikec302@fedoraproject.org
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
--- On Wed, 10/1/08, bruce bedouglas@earthlink.net wrote:
From: bruce bedouglas@earthlink.net Subject: RE: Using all of 4GB RAM... questions and Vista versus Linux... To: "'Community assistance, encouragement, and advice for using Fedora.'" fedora-list@redhat.com Date: Wednesday, October 1, 2008, 4:37 PM i don't know the guts of fedora/rh... but i would imagine that a chunk of the mem space is reserved for system operational functions. as a result, the mem space that you, the app has, is the mem that's left over for apps to play in..
the reserved mem space might be used for swap, mem checking, error checking, os kernel functions, etc...
-----Original Message----- From: fedora-list-bounces@redhat.com [mailto:fedora-list-bounces@redhat.com]On Behalf Of Mike Chambers Sent: Wednesday, October 01, 2008 9:33 AM To: Community assistance, encouragement,and advice for using Fedora. Subject: Re: Using all of 4GB RAM... questions and Vista versus Linux...
On Wed, 2008-10-01 at 11:17 -0500, Richard Shaw wrote:
Maybe someone can word this better than I but here it
goes. The memory
limit is not really tied to the OS "TYPE"
(i.e. Windows XP/Vista,
Linux, etc) but more to the architecture (32-bit vs.
64-bit). As far
as I'm aware, all 32-bit OS's will have this
limitation and all 64-bit
OS's will not. You can get Windows XP, Vista or
Linux in both 32 and
64-bit flavors.
So to answer your question (c), yes, if you switch to
a 64bit version
of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
-- Mike Chambers Fedora Project - Ambassador, Bug Zapper, Tester, User, etc.. mikec302@fedoraproject.org
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
--
BE CAREFUL the top posting leprechaun will get you!
fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
On Wed, 2008-10-01 at 09:49 -0700, Fred Silsbee wrote:
--- On Wed, 10/1/08, bruce bedouglas@earthlink.net wrote:
From: bruce bedouglas@earthlink.net Subject: RE: Using all of 4GB RAM... questions and Vista versus Linux... To: "'Community assistance, encouragement, and advice for using Fedora.'" fedora-list@redhat.com Date: Wednesday, October 1, 2008, 4:37 PM i don't know the guts of fedora/rh... but i would imagine that a chunk of the mem space is reserved for system operational functions. as a result, the mem space that you, the app has, is the mem that's left over for apps to play in..
the reserved mem space might be used for swap, mem checking, error checking, os kernel functions, etc...
-----Original Message----- From: fedora-list-bounces@redhat.com [mailto:fedora-list-bounces@redhat.com]On Behalf Of Mike Chambers Sent: Wednesday, October 01, 2008 9:33 AM To: Community assistance, encouragement,and advice for using Fedora. Subject: Re: Using all of 4GB RAM... questions and Vista versus Linux...
On Wed, 2008-10-01 at 11:17 -0500, Richard Shaw wrote:
Maybe someone can word this better than I but here it
goes. The memory
limit is not really tied to the OS "TYPE"
(i.e. Windows XP/Vista,
Linux, etc) but more to the architecture (32-bit vs.
64-bit). As far
as I'm aware, all 32-bit OS's will have this
limitation and all 64-bit
OS's will not. You can get Windows XP, Vista or
Linux in both 32 and
64-bit flavors.
So to answer your question (c), yes, if you switch to
a 64bit version
of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
-- Mike Chambers Fedora Project - Ambassador, Bug Zapper, Tester, User, etc.. mikec302@fedoraproject.org
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
--
BE CAREFUL the top posting leprechaun will get you!
Chomp.
poc
Fred Silsbee:
BE CAREFUL the top posting leprechaun will get you!
Patrick O'Callaghan:
Chomp.
If you're going to byte, please also snip.
Tim... Playing mail catchup after being on holidays for a few days, and the *APPALLING* way many people post and reply is not helping! My delete key is getting a workout. If I can't easily read your post, it's getting deleted.
--- On Fri, 10/3/08, Tim ignored_mailbox@yahoo.com.au wrote:
From: Tim ignored_mailbox@yahoo.com.au Subject: RE: Using all of 4GB RAM... questions and Vista versus Linux... To: "Community assistance, encouragement, and advice for using Fedora." fedora-list@redhat.com Date: Friday, October 3, 2008, 1:54 AM Fred Silsbee:
BE CAREFUL the top posting leprechaun will get
you!
Patrick O'Callaghan:
Chomp.
If you're going to byte, please also snip.
Tim... Playing mail catchup after being on holidays for a few days, and the *APPALLING* way many people post and reply is not helping! My delete key is getting a workout. If I can't easily read your post, it's getting deleted.
the pox be upon top posters
and a diseased goat enter their sister's tent
I always double check to make sure my email is in good order!
-- [tim@localhost ~]$ uname -r 2.6.26.3-29.fc9.i686
Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists.
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
On Wednesday 01 October 2008, Mike Chambers wrote:
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
Is your system using part of the memory for on-board video? That's the most logical explanation.
On Wed, 2008-10-01 at 13:53 -0400, John Aldrich wrote:
On Wednesday 01 October 2008, Mike Chambers wrote:
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
Is your system using part of the memory for on-board video? That's the most logical explanation.
I don't know. I'm running the Nvidia 8800, which has 512KB on board How does one check if the video card is using RAM ?
On Wednesday 01 October 2008, Linuxguy123 wrote:
Is your system using part of the memory for on-board video? That's the most logical explanation.
I don't know. I'm running the Nvidia 8800, which has 512KB on board How does one check if the video card is using RAM ?
If you've got a separate video card, then that's not the answer. Although some motherboards (including mine) come with an on-board video adapter, it does not sound like yours does.
On Wed, Oct 1, 2008 at 11:32 AM, Mike Chambers mike@miketc.net wrote:
On Wed, 2008-10-01 at 11:17 -0500, Richard Shaw wrote:
Maybe someone can word this better than I but here it goes. The memory limit is not really tied to the OS "TYPE" (i.e. Windows XP/Vista, Linux, etc) but more to the architecture (32-bit vs. 64-bit). As far as I'm aware, all 32-bit OS's will have this limitation and all 64-bit OS's will not. You can get Windows XP, Vista or Linux in both 32 and 64-bit flavors.
So to answer your question (c), yes, if you switch to a 64bit version of Linux you will be able to use all 4GB.
Does that work on only 4Gb or more? I have 2Gb Ram, and running 64bit, and still only see 1.8Gb of memory, as it did with 32bit as well.
In that case something is definitely reserving some memory. I often see this in systems with onboard video which usually do not have dedicated video ram.
Richard.
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
[fedora@localhost ~]$ free -m total used free shared buffers cached Mem: 3969 1286 2682 0 143 827 -/+ buffers/cache: 315 3654 Swap: 1992 0 1992
Here is what it looks like under my 32 bit installation:
$ free -m total used free shared buffers cached Mem: 3034 978 2055 0 33 619 -/+ buffers/cache: 326 2708 Swap: 1992 0 1992
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
"Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
This message probably means to say that the memory is available above the 4GB address limit of 32 bit programs and that 32 bit applications can't access it. But its there for 64bit applications to use because it probably gets remapped above the 4GB boundary and 64 bit applications can address it there.
The only difference between the two tests is that with the 32bit installation I am running 2 1680x1050 monitors side by side, whereas with the 64 bit test both monitors were running but they were displaying the same thing. I don't think this makes a difference in the amount of memory available because I ran it earlier in the week without the 2nd monitor and it still showed it was only using 3GB.
It looks like the 64bit version of Linux makes use of all the available RAM, whereas the 32bit version only uses the first 3GB.
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
Thanks
On Wed, 2008-10-01 at 13:56 -0400, Linuxguy123 wrote:
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
[fedora@localhost ~]$ free -m total used free shared buffers cached Mem: 3969 1286 2682 0 143 827 -/+ buffers/cache: 315 3654 Swap: 1992 0 1992
Here is what it looks like under my 32 bit installation:
$ free -m total used free shared buffers cached Mem: 3034 978 2055 0 33 619 -/+ buffers/cache: 326 2708 Swap: 1992 0 1992
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
"Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
This message probably means to say that the memory is available above the 4GB address limit of 32 bit programs and that 32 bit applications can't access it. But its there for 64bit applications to use because it probably gets remapped above the 4GB boundary and 64 bit applications can address it there.
The only difference between the two tests is that with the 32bit installation I am running 2 1680x1050 monitors side by side, whereas with the 64 bit test both monitors were running but they were displaying the same thing. I don't think this makes a difference in the amount of memory available because I ran it earlier in the week without the 2nd monitor and it still showed it was only using 3GB.
It looks like the 64bit version of Linux makes use of all the available RAM, whereas the 32bit version only uses the first 3GB.
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
---- sorry - reinstall is your only option
Craig
On Wed, 2008-10-01 at 13:10 -0700, Craig White wrote:
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
sorry - reinstall is your only option
Reinstall the kernel or the whole "OS" including the applications ?
How do I "reinstall" and get the exact same set of applications that I currently have and keep all my user data ?
I was hoping that I could change a setting from i386 to x86_64 and some magic would occur whereby everything got replaced. Even if I had to write a yum script to do it ?
Thanks.
On Wed, 2008-10-01 at 14:19 -0400, Linuxguy123 wrote:
On Wed, 2008-10-01 at 13:10 -0700, Craig White wrote:
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
sorry - reinstall is your only option
Reinstall the kernel or the whole "OS" including the applications ?
How do I "reinstall" and get the exact same set of applications that I currently have and keep all my user data ?
I was hoping that I could change a setting from i386 to x86_64 and some magic would occur whereby everything got replaced. Even if I had to write a yum script to do it ?
---- reinstall the Whole OS
you probably could just check out /root/anaconda-ks.cfg for a clue as to what packages to install. You could actually feed that kickstart script to the installer for a repeat with the 86_64 sources.
Craig
--- On Wed, 10/1/08, Craig White craigwhite@azapple.com wrote:
From: Craig White craigwhite@azapple.com Subject: Re: 64 Bit Linux shows 4GB... was Using all of 4GB RAM... To: "Community assistance, encouragement, and advice for using Fedora." fedora-list@redhat.com Date: Wednesday, October 1, 2008, 8:37 PM On Wed, 2008-10-01 at 14:19 -0400, Linuxguy123 wrote:
On Wed, 2008-10-01 at 13:10 -0700, Craig White wrote:
So... what is the easiest way to convert my
32 bit installation to 64
bits ? Please don't tell me to
reinstall because I just did that
earlier this week to go from F9 back to F8.
sorry - reinstall is your only option
Reinstall the kernel or the whole "OS"
including the applications ?
How do I "reinstall" and get the exact same
set of applications that I
currently have and keep all my user data ?
I was hoping that I could change a setting from i386
to x86_64 and some
magic would occur whereby everything got replaced.
Even if I had to
write a yum script to do it ?
reinstall the Whole OS
you probably could just check out /root/anaconda-ks.cfg for a clue as to what packages to install. You could actually feed that kickstart script to the installer for a repeat with the 86_64 sources.
Craig
reinstall
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
On Wednesday 01 October 2008, Linuxguy123 wrote:
sorry - reinstall is your only option
Reinstall the kernel or the whole "OS" including the applications ?
How do I "reinstall" and get the exact same set of applications that I currently have and keep all my user data ?
I was hoping that I could change a setting from i386 to x86_64 and some magic would occur whereby everything got replaced. Even if I had to write a yum script to do it ?
Well, what you could do would be to reinstall, but don't reformat. At least that way you'd keep all your "user" data. That's typically what I do, since I have a separate partition for /home.
On Wed, Oct 1, 2008 at 4:01 PM, John Aldrich john@chattanooga.net wrote:
On Wednesday 01 October 2008, Linuxguy123 wrote:
sorry - reinstall is your only option
Reinstall the kernel or the whole "OS" including the applications ?
How do I "reinstall" and get the exact same set of applications that I currently have and keep all my user data ?
I was hoping that I could change a setting from i386 to x86_64 and some magic would occur whereby everything got replaced. Even if I had to write a yum script to do it ?
Well, what you could do would be to reinstall, but don't reformat. At least that way you'd keep all your "user" data. That's typically what I do, since I have a separate partition for /home.
I wonder what would happen if you did an "Upgrade" from F8 32-bit to F8 x86_64? Theoretically wouldn't it try and keep all the same packages installed but just replace them with their 64bit counterpart?
Richard
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
sorry - reinstall is your only option
Depends how crazy you are feeling but I would suggest doing a reinstall. If you really really want you can force install (with rpm --forcearch) parallel 64bit versions of the core setup but its pretty hairy.
Alan
On Wednesday 01 October 2008 12:56:40 pm Linuxguy123 wrote:
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
So... what is the easiest way to convert my 32 bit installation to 64 bits ? Please don't tell me to reinstall because I just did that earlier this week to go from F9 back to F8.
you could try running the PAE kernel.
edit /etc/sysconfig/kernel and change prefered to kernel-PAE then "yum install kernel-PAE" that might be enough to give you access to all 4 gb since it seems to not be a hardware limitation but a 32 bit os limitation.
Dennis
Linuxguy123 wrote:
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
[fedora@localhost ~]$ free -m total used free shared buffers cached Mem: 3969 1286 2682 0 143 827 -/+ buffers/cache: 315 3654 Swap: 1992 0 1992
Here is what it looks like under my 32 bit installation:
$ free -m total used free shared buffers cached Mem: 3034 978 2055 0 33 619 -/+ buffers/cache: 326 2708 Swap: 1992 0 1992
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
Could it be simply that free does not show the space needed by the kernel.... which needs (at least some parts of it) to be constantly in memory. I do not think that 127Mb is such a big price to pay for the kernel. Note that to use your memory in a single process you need x86-64. The standard x86 linux limits the processes memory to 2Gb.
On Thu, Oct 2, 2008 at 2:37 AM, Theodore Papadopoulo Theodore.Papadopoulo@sophia.inria.fr wrote:
Linuxguy123 wrote:
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
[fedora@localhost ~]$ free -m total used free shared buffers cached Mem: 3969 1286 2682 0 143 827 -/+ buffers/cache: 315 3654 Swap: 1992 0 1992
Here is what it looks like under my 32 bit installation:
$ free -m total used free shared buffers cached Mem: 3034 978 2055 0 33 619 -/+ buffers/cache: 326 2708 Swap: 1992 0 1992
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
Could it be simply that free does not show the space needed by the kernel.... which needs (at least some parts of it) to be constantly in memory. I do not think that 127Mb is such a big price to pay for the kernel. Note that to use your memory in a single process you need x86-64. The standard x86 linux limits the processes memory to 2Gb.
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If you run the PAE kernel, then all of your memory will be seen and used by the OS. It is what I use when I use a desktop system so that I do not have to deal with x86_64 type desktop issues.
On Thursday 02 October 2008, Adam Hough wrote:
On Thu, Oct 2, 2008 at 2:37 AM, Theodore Papadopoulo
Theodore.Papadopoulo@sophia.inria.fr wrote:
Linuxguy123 wrote:
Dennis Gilmore suggested that I boot a 64 bit Live CD to see what it said about memory usage. So I did:
[fedora@localhost ~]$ free -m total used free shared buffers cached Mem: 3969 1286 2682 0 143 827 -/+ buffers/cache: 315 3654 Swap: 1992 0 1992
Here is what it looks like under my 32 bit installation:
$ free -m total used free shared buffers cached Mem: 3034 978 2055 0 33 619 -/+ buffers/cache: 326 2708 Swap: 1992 0 1992
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
Could it be simply that free does not show the space needed by the kernel.... which needs (at least some parts of it) to be constantly in memory. I do not think that 127Mb is such a big price to pay for the kernel. Note that to use your memory in a single process you need x86-64. The standard x86 linux limits the processes memory to 2Gb.
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
If you run the PAE kernel, then all of your memory will be seen and used by the OS. It is what I use when I use a desktop system so that I do not have to deal with x86_64 type desktop issues.
I am now running it, seems fine. Now if we could figgur out why grub takes about a minute to present the boot menu.
I did just now update the bios, and now the blinking display if using the hdmi cable for about the first 5 minutes seems to be gone.
Thanks.
On Thu, 2008-10-02 at 10:44 -0400, Gene Heskett wrote:
Now if we could figgur out why grub takes about a minute to present the boot menu.
Do you have a collection of connected bootable drives, or interfaces for drives (even if none are plugged into them). If so, it could be trying to enumerate them before proceeding.
--- On Fri, 10/3/08, Tim ignored_mailbox@yahoo.com.au wrote:
From: Tim ignored_mailbox@yahoo.com.au Subject: Re: 64 Bit Linux shows 4GB... was Using all of 4GB RAM... To: "Community assistance, encouragement, and advice for using Fedora." fedora-list@redhat.com Date: Friday, October 3, 2008, 2:01 AM On Thu, 2008-10-02 at 10:44 -0400, Gene Heskett wrote:
Now if we could figgur out why grub takes about a
minute to present
the boot menu.
Do you have a collection of connected bootable drives, or interfaces for drives (even if none are plugged into them). If so, it could be trying to enumerate them before proceeding.
perhaps a bad entry (drive name) in the grub table! Here is mine /boot/grub/grub.conf
# grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00 # initrd /initrd-version.img #boot=/dev/sdb default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Fedora (2.6.26.5-45.fc9.i686) root (hd1,0) kernel /vmlinuz-2.6.26.5-45.fc9.i686 ro root=/dev/VolGroup00/LogVol00 rhgb quiet initrd /initrd-2.6.26.5-45.fc9.i686.img title Fedora (2.6.26.3-29.fc9.i686) root (hd1,0) kernel /vmlinuz-2.6.26.3-29.fc9.i686 ro root=/dev/VolGroup00/LogVol00 rhgb quiet initrd /initrd-2.6.26.3-29.fc9.i686.img title Fedora (2.6.25.14-108.fc9.i686) root (hd1,0) kernel /vmlinuz-2.6.25.14-108.fc9.i686 ro root=/dev/VolGroup00/LogVol00 rhgb quiet initrd /initrd-2.6.25.14-108.fc9.i686.img title XP Professional rootnoverify (hd0,0) chainloader +1
When I installed F9, I found the question (sounds like)
"what drive do you want to boot to"
ambivalent .
I have XP Prof on scsi a and F9 on scsi b
I think one boots to scsi a first to get the grub stuff and then to F9 on scsi b.
I had to do some swift grub admin to clear up that mess using the rescue disk = install disk.
-- [tim@localhost ~]$ uname -r 2.6.26.3-29.fc9.i686
Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists.
-- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
On Wed, 2008-10-01 at 13:56 -0400, Linuxguy123 wrote:
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
"Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
That sort of disclaimer doesn't mean anything technically. It's warning the average user that having 4 gigs of RAM in their PC doesn't mean that they'll have 4 gigs of *free* RAM, some of it will be used (when your OS loads, it uses some of your RAM, and some OSs use lots of your RAM).
You'd have a different sort of warning/disclaimer for hardware that couldn't make use of all RAM, regardless of the software you run on it.
Tim wrote:
On Wed, 2008-10-01 at 13:56 -0400, Linuxguy123 wrote:
I appear to gain 935MB of RAM running the 64 bit version. This is in spite of the spec sheet on my laptop saying:
"Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
That sort of disclaimer doesn't mean anything technically. It's warning the average user that having 4 gigs of RAM in their PC doesn't mean that they'll have 4 gigs of *free* RAM, some of it will be used (when your OS loads, it uses some of your RAM, and some OSs use lots of your RAM).
Then why does it say 32-bit operating systems? 64-bit operating systems have baseline memory demands too.
Matt Flaschen
Then why does it say 32-bit operating systems? 64-bit operating systems have baseline memory demands too.
What is usually going on in those cases is that with 4GB RAM you need some space for PCI etc below the 4GB boundary, that means part of the RAM has to be mapped above the 4GB boundary which most 32bit OS can't reach (hugemem Linux kernels can but there is a big performance cost to such antics)
Alan Cox wrote:
Then why does it say 32-bit operating systems? 64-bit operating systems have baseline memory demands too.
What is usually going on in those cases is that with 4GB RAM you need some space for PCI etc below the 4GB boundary, that means part of the RAM has to be mapped above the 4GB boundary which most 32bit OS can't reach (hugemem Linux kernels can but there is a big performance cost to such antics)
You probably understand this better than I do, but I have never been able to find enough performance difference in PAE vs. default kernels to worry me, at least using my normal applications. I have measured run times and CPU (back around 2.6.22) and found the overhead was "measurable but not noticeable," down in the "few percent" range. I suspect you have something bigger in mind when you say "big performance cost," so could you expand on that? Is there some type of use which would trigger performance issues not more than compensated by using RAM instead of swapping?
I'm writing this in a VM running FC9 under a native "2.6.22.14-72.fc6PAE" kernel which is heavily used in native mode using all 4GB memory. I did measure this against both the non-PAE 32 bit kernel and x86_64 kernel for desktop, gimp, and kernel builds.
You probably understand this better than I do, but I have never been able to find enough performance difference in PAE vs. default kernels to worry me, at
PAE costs you a few percent on tlb loads. The big hit with > 1GB RAM is the cost of the remapping of user pages and the TLB flushes it causes, and on the 'hugemem' > 4GB referencing kernel that grows a lot more as well as getting a lot of problems with 32bit capable I/O devices and Intel processors with non IOMMU.
It depends a lot on workload and CPU variant.
I'm writing this in a VM running FC9 under a native "2.6.22.14-72.fc6PAE" kernel which is heavily used in native mode using all 4GB memory. I did measure this against both the non-PAE 32 bit kernel and x86_64 kernel for desktop, gimp, and kernel builds.
If you are using a VM you've already totally shot your page table performance to bits so it won't make any difference.
Alan
Alan Cox wrote:
You probably understand this better than I do, but I have never been able to find enough performance difference in PAE vs. default kernels to worry me, at
PAE costs you a few percent on tlb loads. The big hit with > 1GB RAM is the cost of the remapping of user pages and the TLB flushes it causes, and on the 'hugemem' > 4GB referencing kernel that grows a lot more as well as getting a lot of problems with 32bit capable I/O devices and Intel processors with non IOMMU.
It depends a lot on workload and CPU variant.
I'm writing this in a VM running FC9 under a native "2.6.22.14-72.fc6PAE" kernel which is heavily used in native mode using all 4GB memory. I did measure this against both the non-PAE 32 bit kernel and x86_64 kernel for desktop, gimp, and kernel builds.
If you are using a VM you've already totally shot your page table performance to bits so it won't make any difference.
As noted, I did the testing on PAE, default, and x86_64 on the bare iron, and didn't really see any significant performance changes. The differences were all down just at the limits of noise in repeated runs, in the 2-3% range. For many cases the performance benefit from using more memory is vastly greater than the small loss in memory management overhead.
I have the feeling that running 32 bit apps under a 64 bit kernel is actually slower than PAE, but again it's down in the noise. Thanks for your input.
On Wednesday 01 October 2008 07:54:51 am Linuxguy123 wrote:
I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of RAM.
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
depends on the hardware
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
they are limited to what the bios will give them access to same as linux.
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
maybe maybe not, I have a dell latitude that while a 64 bit system has a 32 bit memory controller. so it only sees 3.25gb due to the memory hole. with no way to access it . this is a hardware limitation. and cant be worked around.
the issue here is probably hardware related and likely needs to be worked around in hardware. if HP doesnt allow that then you get what you see. you can always try a 64 bit livecd to see if things work better for you there.
Dennis
On Wed, 2008-10-01 at 11:54 -0500, Dennis Gilmore wrote:
the issue here is probably hardware related and likely needs to be worked around in hardware. if HP doesnt allow that then you get what you see. you can always try a 64 bit livecd to see if things work better for you there.
Great suggestion. Thanks for replying.
Linuxguy123 wrote:
I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of RAM.
$ uname -a Linux localhost.localdomain 2.6.26.3-14.fc8 #1 SMP Wed Sep 3 03:40:05 EDT 2008 i686 i686 i386 GNU/Linux
Even though I have 4GB of RAM installed, Linux appears to only be using 3GB of it.
$ free -t total used free shared buffers cached Mem: 3106944 777056 2329888 0 60608 419608 -/+ buffers/cache: 296840 2810104 Swap: 2040244 0 2040244 Total: 5147188 777056 4370132
I've read in other posts to this group that the cause of this is that the BIOS remaps the some (1GB) of memory to serve as address space for PCI devices, thus creating a memory "hole".
I understand that some BIOSes allow one to remap those devices elsewhere in the map. My BIOS does NOT allow that option.
There is really no other place to put the PCI devices except in the lower 4GB since anywhere else would result in 32-bit OSes being unable to access them.
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
The chipset is not capable of remapping under certain conditions, or the bios won't do it because it would cause lower memory availability with windows. Some bios can only remap entire dimms, and that would result in less memory for a 32-bit only OS so they don't do it even though it would result in more memory for a 64-bit/PAE os.
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
In the case of a bios limitation they would also be limited to only 3GB.
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Some bioses will remap memory to above 4GB, but often only if a certain option is set, and often these options are only available on server class MB's, though these options may now be showing up on desktops since desktops can now support more memory.
You would have to boot a PAE or 64bit kernel and mess around with bios options to see if you bios can do it, it may or may not be able to do it in a useful way. And of course the bios options are poorly documented.
Roger
Thanks
On Wed, 2008-10-01 at 12:13 -0500, Roger Heflin wrote:
The chipset is not capable of remapping under certain conditions, or the bios won't do it because it would cause lower memory availability with windows. Some bios can only remap entire dimms, and that would result in less memory for a 32-bit only OS so they don't do it even though it would result in more memory for a 64-bit/PAE os.
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
In the case of a bios limitation they would also be limited to only 3GB.
Here is the spec sheet for my laptop. http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01490775&cc=us&...
It says: "Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
This machine ships with a 64 bit version of Vista. I didn't think to check what the available memory was under Vista. I don't have it installed anymore.
Linuxguy123 wrote:
Here is the spec sheet for my laptop. http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01490775&cc=us&...
It says: "Memory 4096 MB Memory Max Up to 4GB DDR2 (Up to 1 GB may not be available due to 32-bit operating system resource requirements)"
That does not look positive. Since the machine only supports up to 4GB the bios would be less likely to go to the trouble of adding options to support remapping, and that statement appears to indicate that they did not worry about PAE/64bit OSes. You might see if there is a bios update that changes things.
Also the major vendors appear to have less options to tune things in the bios than many other MB makers.
Roger
Linuxguy123 wrote:
I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of RAM.
$ uname -a Linux localhost.localdomain 2.6.26.3-14.fc8 #1 SMP Wed Sep 3 03:40:05 EDT 2008 i686 i686 i386 GNU/Linux
Even though I have 4GB of RAM installed, Linux appears to only be using 3GB of it.
$ free -t total used free shared buffers cached Mem: 3106944 777056 2329888 0 60608 419608 -/+ buffers/cache: 296840 2810104 Swap: 2040244 0 2040244 Total: 5147188 777056 4370132
I've read in other posts to this group that the cause of this is that the BIOS remaps the some (1GB) of memory to serve as address space for PCI devices, thus creating a memory "hole".
I understand that some BIOSes allow one to remap those devices elsewhere in the map. My BIOS does NOT allow that option.
Questions:
a) On machines that do not allow PCI remapping, is the processor physically disallowed from accessing that 4GB of RAM ? Ie have the address lines from the processor been disconnected from that RAM due to being connected to the PCI devices ?
b) How do XP and Vista handle this ? Are they limited to 3GB of RAM too ?
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Maybe, but that's the solution of last resort. If you have the x86_64 "live" CD it's worth looking, but I think there are (at least) two better solutions. First is the PAE kernel. You don't need to go diddling your setup to try it, just open a terminal and run yum install kernel-PAE to get a PAE kernel. Then reboot, and when the boot menu comes up, select the PAE version. Run the free command and see if it found your memory.
The next step is to wait for the 2.6.27 kernel. WARNING: if you have e1000 hardware, don't try this kernel until the issues have been resolved, see the kernel list, this kernel *may* make your e1000 into a brick by eating the flash firmware. It's being worked on, it's low probability, but wait as week, good people are trying it.
The reason 2.6.27 is desirable for you is that a lot of work has gone into the MTRR register mapping, and it *may* be able to describe your memory where the 2.6.26 can't. Take that for what it's worth, I would try PAE now, and wait until 2.6.27 is patched (unless you have a totally different hardware).
There are really no serious benefits to 64 bit unless you need to run very large user mode application programs. For less than 4GB memory 32 bit might be a bit faster due to less cache pressure, and for large memory the difference between PAE and 64 bit native is down in the noise, and 32 bit applications are generally faster (cache again).
Try the easy solutions first before you go 64 bit, and read about the tricks needed to run 32 bit apps in 64 bit (see threads on "my flash doesn't work" and similar).
On Wed, 2008-10-01 at 18:26 -0400, Bill Davidsen wrote:
c) I am running the 32 bit version of Linux. Would it make any difference to my RAM access if I ran the 64 bit version ?
Maybe, but that's the solution of last resort. If you have the x86_64 "live" CD it's worth looking, but I think there are (at least) two better solutions. First is the PAE kernel. You don't need to go diddling your setup to try it, just open a terminal and run yum install kernel-PAE to get a PAE kernel. Then reboot, and when the boot menu comes up, select the PAE version. Run the free command and see if it found your memory.
The next step is to wait for the 2.6.27 kernel. WARNING: if you have e1000 hardware, don't try this kernel until the issues have been resolved, see the kernel list, this kernel *may* make your e1000 into a brick by eating the flash firmware. It's being worked on, it's low probability, but wait as week, good people are trying it.
The reason 2.6.27 is desirable for you is that a lot of work has gone into the MTRR register mapping, and it *may* be able to describe your memory where the 2.6.26 can't. Take that for what it's worth, I would try PAE now, and wait until 2.6.27 is patched (unless you have a totally different hardware).
Great post. Thanks for all the advice. I will wait and see how 2.6.72 works.
LG
| From: Mike Chambers mike@miketc.net
| I have 2Gb Ram, and running 64bit, | and still only see 1.8Gb of memory, as it did with 32bit as well.
You probably have a shared video device buffer.
If you look at dmesg output, you can kind of puzzle out how the BIOS maps memory. Here's from one of my machines:
BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) BIOS-e820: 00000000000e7000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000003ffc0000 (usable) BIOS-e820: 000000003ffc0000 - 000000003ffd0000 (ACPI data) BIOS-e820: 000000003ffd0000 - 0000000040000000 (ACPI NVS) BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved) BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved) BIOS-e820: 00000000ff7c0000 - 0000000100000000 (reserved)
This machine has 1GiB of RAM at 00000000-3fffffff Certain parts of it are reserved by the BIOS.
Another good hint is /proc/mtrr: reg00: base=0x00000000 ( 0MB), size=1024MB: write-back, count=1 reg01: base=0xf0000000 (3840MB), size= 128MB: write-combining, count=1 reg02: base=0xd0000000 (3328MB), size= 256MB: write-combining, count=2
reg00 is for my RAM. The other two are for video buffers. (A little odd since the first video buffer is for an on-board controller that is turned off, I think.)
lspci can be used to find the buffer addresses for video cards.
| From: Dennis Gilmore dennis@ausil.us
| I have a dell latitude that while a 64 bit system has a 32 | bit memory controller. so it only sees 3.25gb due to the memory hole. with | no way to access it . this is a hardware limitation. and cant be worked | around.
This may not be the case. PAE has been around since the Pentium Pro. It allows way more than 64GiB: http://en.wikipedia.org/wiki/Physical_Address_Extension
The "chipset" might be a problem but I think that most that cannot handle mapping to above 4G only allow 2G of RAM to be installed.
| the issue here is probably hardware related and likely needs to be worked | around in hardware.
I don't think so. But it could be.
I have an Acer notebook that claims to support 4G but locks up (pre BIOS boot screen) if you actually do put 4G in it. Others experience this too. (There is evidence that this is a BIOS bug.) Acer says "not our problem". So manufacturers do do stupid things.
| if HP doesnt allow that then you get what you see. you | can always try a 64 bit livecd to see if things work better for you there.
Right. Or just try a PAE kernel (as Bill Davidsen explained).
(Vista doesn't know how to use PAE. Vista 32 SP1 adds the ability to report more than 3.x G of RAM, but not how to use it!)
But looking at /proc/mtrr is probably faster. Look for something above ffffffff.
| From: Roger Heflin rogerheflin@gmail.com
| Some bioses will remap memory to above 4GB, but often only if a certain option | is set, and often these options are only available on server class MB's, | though these options may now be showing up on desktops since desktops can now | support more memory.
In my modest experience, all modern BIOS remap. Some (but not consumer HP ones) have an option to turn off remapping.
The main reason you might want to suppress remapping is to work around MTRR problems (see below).
| From: Bill Davidsen davidsen@tmr.com
| The reason 2.6.27 is desirable for you is that a lot of work has gone into the | MTRR register mapping, and it *may* be able to describe your memory where the | 2.6.26 can't. Take that for what it's worth, I would try PAE now, and wait | until 2.6.27 is patched (unless you have a totally different hardware).
While waiting, if you have MTRR problems, you could try my userland hack to fix them. ftp://ftp.cs.utoronto.ca/pub/hugh/mtrr-uncover-2008oct01.tgz
Slightly tricky, but if you are stuck, it is useful. The main trickiness is that it has to be run early, before X starts. It also may need to be run before the frame buffer console driver which is probably best solved by not using the frame buffer console driver.
It can also be used just to show if you have a problem.
| There are really no serious benefits to 64 bit unless you need to run very | large user mode application programs.
True. But the meaning of "very large" has a way of creeping up.
I always use 64-bit when I can. Not much benefit, not much cost.