32 bit 11.1 kernel, default or pae?

Vahis · External Since: May 19, 2007 Posts: 79

I'm setting up a box that can temporarily replace my "production"
machine.
The replacement is an old 32 bit AMD Athlon w 2 GB RAM.

The initial default installation chooses to install the pae kernel in it.

It has an old Nvidia GPU, so I add the driver.
1-click install for legacy cards wants to change the kernel to
default.

Is there any real difference in default and pae in case of this old CPU
and only 2 GB of RAM?

If there _is_ something, which is better?

Vahis
--
"Sunrise 4:48am (EEST), sunset 10:04pm (EEST) at Espoo, Finland (17:15 hours daylight)"
http://waxborg.servepics.com
Linux 2.6.25.20-0.4-default #1 SMP 2009-06-01 09:57:12 +0200 x86_64
6:39pm up 42 days 3:13, 11 users, load average: 0.15, 0.18, 0.11

Szymon von Ulezalka · External Since: Jul 26, 2009 Posts: 2

On 26 Lip, 16:47, Vahis <waxb....TakeThisOut@gmail.com.invalid> wrote:
> I'm setting up a box that can temporarily replace my "production"
> machine.
> The replacement is an old 32 bit AMD Athlon w 2 GB RAM.
>
> The initial default installation chooses to install the pae kernel in it.
>
> It has an old Nvidia GPU, so I add the driver.
> 1-click install for legacy cards wants to change the kernel to
> default.
>
> Is there any real difference in default and pae in case of this old CPU
> and only 2 GB of RAM?
>
> If there _is_ something, which is better?
>
> Vahis
> --
> "Sunrise 4:48am (EEST), sunset 10:04pm (EEST) at Espoo, Finland (17:15 hours daylight)"http://waxborg.servepics.com
> Linux 2.6.25.20-0.4-default #1 SMP 2009-06-01 09:57:12 +0200 x86_64
> 6:39pm up 42 days 3:13, 11 users, load average: 0.15, 0.18, 0.11

using pae is, basically, reasonless on machines with less than 4gb of
ram.
sure, you can use it 'just because' - it wont harm, but also wont
provide any improvement, unless you wanna use NX /no execute or
something like that ;p/ bit- but in that case, system probably will be
a bit slower.

David Bolt · External Since: Feb 14, 2006 Posts: 526

On Sun, 26 Jul 2009, Vahis wrote:-

>I'm setting up a box that can temporarily replace my "production"
>machine.
>The replacement is an old 32 bit AMD Athlon w 2 GB RAM.
>
>The initial default installation chooses to install the pae kernel in it.

I noticed that it's also the default on the last 11.2 milestone[0], so
it seems that this is going to end up as the default kernel rather than
the "default" 32bit kernel.

>It has an old Nvidia GPU, so I add the driver.
>1-click install for legacy cards wants to change the kernel to
>default.

Don't you hate when that sort of think happens.

>Is there any real difference in default and pae in case of this old CPU
>and only 2 GB of RAM?

Not really. A PAE kernel is only really required to access 4GB, or more,
on a 32bit system. Since you don't have 4GB, there's no reason for
having the PAE kernel.

[0] 3 not 4. Still got to install milestone 4.

Regards,
David Bolt

--
Team Acorn: http://www.distributed.net/ OGR-NG @ ~100Mnodes RC5-72 @ ~1Mkeys/s
openSUSE 10.3 32b | openSUSE 11.0 32b | |
openSUSE 10.3 64b | openSUSE 11.0 64b | openSUSE 11.1 64b |
RISC OS 3.6 | RISC OS 3.11 | openSUSE 11.1 PPC | TOS 4.02

Vahis · External Since: May 19, 2007 Posts: 79

On 2009-07-26, David Bolt <blacklist-me.RemoveThis@davjam.org> wrote:
> On Sun, 26 Jul 2009, Vahis wrote:-
>
>>I'm setting up a box that can temporarily replace my "production"
>>machine.
>>The replacement is an old 32 bit AMD Athlon w 2 GB RAM.
>>
>>The initial default installation chooses to install the pae kernel in it.
>
> I noticed that it's also the default on the last 11.2 milestone[0], so
> it seems that this is going to end up as the default kernel rather than
> the "default" 32bit kernel.

I don't see why it shouldn't. I haven't read of any problems with it.
>
>>It has an old Nvidia GPU, so I add the driver.
>>1-click install for legacy cards wants to change the kernel to
>>default.
>
> Don't you hate when that sort of think happens.

I guess next time I'll think twice before using those 1-click things.
This wasn't that bad but as they're meant for beginners they can cause
confusion. This could have just as well ended up to non bootable system.
I think the 1-click install doesn't work correctly in this case.

The change of kernel was unnecessary. That script should check the
kernel and install suitable versions for it instead of changing the
kernel.

Anyway, the kernel was installed, asking for a boot of course.
I did, to see what's cooking.
It had been added to the boot menu, correctly though.

I still chose to boot the original pae kernel, and removed then the
new default ones from the list.

Then I removed the newly installed kernel, as well as the Nvidia stuff.
Then I added the pae versions of Nvidia stuff.
This time no reboot, of course.
The I ran sax2 and I was cool.

I shouldn't have needed the reboot, but I wanted to see whether the boot
loader had been trashed or not.
>
>>Is there any real difference in default and pae in case of this old CPU
>>and only 2 GB of RAM?
>
> Not really. A PAE kernel is only really required to access 4GB, or more,
> on a 32bit system. Since you don't have 4GB, there's no reason for
> having the PAE kernel.

I didn't think so.
If the initial installation would have installed the default version
this might have gone without notice.

I have no idea how the installation script determines the need of the
kernel version.
I don't remember seeing an option to choose it myself anyway.
Maybe it's lottery Smile

Vahis
--
"Sunrise 4:48am (EEST), sunset 10:04pm (EEST) at Espoo, Finland (17:15 hours daylight)"
http://waxborg.servepics.com
Linux 2.6.25.20-0.4-default #1 SMP 2009-06-01 09:57:12 +0200 x86_64
10:15pm up 42 days 6:49, 12 users, load average: 0.23, 0.36, 0.60

David Bolt · External Since: Feb 14, 2006 Posts: 526

On Sun, 26 Jul 2009, Vahis wrote:-

>On 2009-07-26, David Bolt <blacklist-me.DeleteThis@davjam.org> wrote:

>> I noticed that it's also the default on the last 11.2 milestone[0], so
>> it seems that this is going to end up as the default kernel rather than
>> the "default" 32bit kernel.
>
>I don't see why it shouldn't. I haven't read of any problems with it.

Having PAE enabled supposedly slows things down a bit. Don't know how
much and, to be honest, I've never really noticed. Then again, I don't
use my machines for time-critical where a few nanoseconds makes a huge
difference, nor do I sit down with some anything to benchmark the
different kernels, so it really doesn't matter to me which kernel is
used. As long as it works with my hardware, and doesn't noticeably slow
down the system, I don't care. If it did, I would.

>> Don't you hate when that sort of think happens.
>
>I guess next time I'll think twice before using those 1-click things.
>This wasn't that bad but as they're meant for beginners they can cause
>confusion. This could have just as well ended up to non bootable system.
>I think the 1-click install doesn't work correctly in this case.

It's been a while since I touched the 1-click installation, but does it
act like a normal installation and give you a change to check the
packages it's going to install/update/remove? Maybe there was a chance
to forcibly retain the PAE kernel and so have the PAE version of the
nVidia drivers.

>The change of kernel was unnecessary. That script should check the
>kernel and install suitable versions for it instead of changing the
>kernel.
>
>Anyway, the kernel was installed, asking for a boot of course.

Should do after any kernel change, so this isn't surprising.

>Then I removed the newly installed kernel, as well as the Nvidia stuff.
>Then I added the pae versions of Nvidia stuff.
>This time no reboot, of course.
>The I ran sax2 and I was cool.
>
>I shouldn't have needed the reboot, but I wanted to see whether the boot
>loader had been trashed or not.

I've met that, although I like to check the config files look to be sane
before letting the system reboot.

>>>Is there any real difference in default and pae in case of this old CPU
>>>and only 2 GB of RAM?
>>
>> Not really. A PAE kernel is only really required to access 4GB, or more,
>> on a 32bit system. Since you don't have 4GB, there's no reason for
>> having the PAE kernel.
>
>I didn't think so.
>If the initial installation would have installed the default version
>this might have gone without notice.

Most likely.

>I have no idea how the installation script determines the need of the
>kernel version.
>I don't remember seeing an option to choose it myself anyway.

I don't think you get to pick unless you go and change the software from
the defaults. And I don't think I've bothered checking which kernel's
going to be installed since one of the 7.x or 8.x releases. The only
time I've changed a kernel from the default was fairly recently after
changing motherboards from a 32bit dual processor board with 2.75GB
installed, to a 64bit board with 4GB installed. The only reason for
changing the kernel then was 10.3 was installed without the big SMP
kernel and so missed the final 1GB of memory. A quick change of kernel
fixed that.

>Maybe it's lottery Smile

I think it's just a case of why not. Most people won't notice and, as
systems are getting more memory, while still sticking with a 32bit
install, having the PAE kernel the default means much less in the way of
"my BIOS reports 4GB but Linux only sees 3GB, where's the missing memory
gone" type of mails to either the mailing list or, if a person bought
the boxed set, when asking for installation help.

Regards,
David Bolt

--
Team Acorn: http://www.distributed.net/ OGR-NG @ ~100Mnodes RC5-72 @ ~1Mkeys/s
openSUSE 10.3 32b | openSUSE 11.0 32b | |
openSUSE 10.3 64b | openSUSE 11.0 64b | openSUSE 11.1 64b |
RISC OS 3.6 | RISC OS 3.11 | openSUSE 11.1 PPC | TOS 4.02

Vahis · External Since: May 19, 2007 Posts: 79

On 2009-07-26, David Bolt <blacklist-me.TakeThisOut@davjam.org> wrote:
> On Sun, 26 Jul 2009, Vahis wrote:-
>
>>On 2009-07-26, David Bolt <blacklist-me.TakeThisOut@davjam.org> wrote:
>
>>> I noticed that it's also the default on the last 11.2 milestone[0], so
>>> it seems that this is going to end up as the default kernel rather than
>>> the "default" 32bit kernel.
>>
>>I don't see why it shouldn't. I haven't read of any problems with it.
>
> Having PAE enabled supposedly slows things down a bit. Don't know how
> much and, to be honest, I've never really noticed.

That's what I've read. Not noticed anything here either.

>>I guess next time I'll think twice before using those 1-click things.
>
> It's been a while since I touched the 1-click installation, but does it
> act like a normal installation and give you a change to check the
> packages it's going to install/update/remove?

It asks to open installation > ok
It asks to add the repo >
It asks wheteher you noticed the things it asked > ok

> Maybe there was a chance
> to forcibly retain the PAE kernel and so have the PAE version of the
> nVidia drivers.

No. That's why it's called 1-click.
>
>>Anyway, the kernel was installed, asking for a boot of course.
>
> Should do after any kernel change, so this isn't surprising.

No, it's not. The only surprise would be if you don't watch its work.

If you grab a mug of coffee in between you'll see that after coming
back.
_Then_ you may face a surprise.

Especially if your system has become non-bootable.
In this case that could well have happened,there was also a trace kernel
added /which I forgot to mention). I don't even know what it is, I don't
usually play around with kernels.

So you install a GPU driver and your kernel is changed plus one added.
>
>>Then I removed the newly installed kernel, as well as the Nvidia stuff.
>>Then I added the pae versions of Nvidia stuff.
>>This time no reboot, of course.
>>The I ran sax2 and I was cool.
>>
>>I shouldn't have needed the reboot, but I wanted to see whether the boot
>>loader had been trashed or not.
>
> I've met that, although I like to check the config files look to be sane
> before letting the system reboot.

I never booted the changed kernel. Or the added new one that I forgot to
mention, I just let it go to show bootloader. I chose the original and
luckily it booted. Then I rolled back.

I have some experiences where rolling back is not possible when you've
gone behind some steps...
>
>>I have no idea how the installation script determines the need of the
>>kernel version.

> I think it's just a case of why not. Most people won't notice and, as
> systems are getting more memory, while still sticking with a 32bit
> install, having the PAE kernel the default means much less in the way of
> "my BIOS reports 4GB but Linux only sees 3GB, where's the missing memory
> gone" type of mails to either the mailing list or, if a person bought
> the boxed set, when asking for installation help.

That's a valid point. Default should be default.
If "PAE" is the default, fine.

But it doesn't make sense to install "PAE" first as default and then change
it to something else by the name "Default".

Especially by a script that fetches and installs a driver. With a couple of
mouse clicks.

I can imagine the feelings in a case where the machine has been running
for a long time and you change the GPU.
In such a case one doesn't want to change a kernel for no reason.

I think that one should be well informed about intended kernel changes.

Vahis
--
"Sunrise 4:50am (EEST), sunset 10:02pm (EEST) at Espoo, Finland (17:11 hours daylight)"
http://waxborg.servepics.com
Linux 2.6.25.20-0.4-default #1 SMP 2009-06-01 09:57:12 +0200 x86_64
9:06am up 42 days 17:40, 13 users, load average: 0.17, 0.17, 0.14