How do I change from a regular kernel to a PAE kernel ?

[linux guy]

My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
want to upgrade to 8 GB of RAM.

I am currently using a 32 bit non PAE kernel.  How do I change to using
a PAE kernel ?

What difference in speed will I notice in doing this ?

Thanks

[Kam Leo]

On Tue, Sep 29, 2009 at 7:27 PM, Linuxguy123  wrote:
> My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> want to upgrade to 8 GB of RAM.
>
> I am currently using a 32 bit non PAE kernel.  How do I change to using
> a PAE kernel ?

yum install kernel-PAE

Note: There may be additional packages which need to be installed,
e.g. kernel-PAE-devel, kmod-nvidia-PAE, etc.

I'm surprised that Anaconda did not detect that your processor was an
i686 and automatically install the PAE kernel.
> What difference in speed will I notice in doing this ?

Don't know.
> Thanks

[linux guy]

On Tue, 2009-09-29 at 20:23 -0700, Kam Leo wrote:
> On Tue, Sep 29, 2009 at 7:27 PM, Linuxguy123  wrote:
> > My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> > want to upgrade to 8 GB of RAM.
> >
> > I am currently using a 32 bit non PAE kernel.  How do I change to using
> > a PAE kernel ?
>
> yum install kernel-PAE
>
> Note: There may be additional packages which need to be installed,
> e.g. kernel-PAE-devel, kmod-nvidia-PAE, etc.

For the record, I did:

yum install kernel-PAE
yum install kernel-PAE-devel

I already had akmod-nvidia installed.  (Which rocks, btw.)

I knew that akmod-nvidia needed a -devel package because I used to
manually build my nvidia drivers.  But I didn't realize that the PAE
kernels had their own -devel, but then I should have because its an
option in the kernel setup if you build your own kernel. DUH !
> I'm surprised that Anaconda did not detect that your processor was an
> i686 and automatically install the PAE kernel.

I've been running this installation since Fedora 8 and I think there was
a time period when the PAE kernels were not available.  And everything
since then has been an upgrade/update, so Anaconda probably isn't
getting to look at what kernel I might need.
> > What difference in speed will I notice in doing this ?

Everything seems faster, but I also changed kernels and there was a yum
update to KDE at the same time, so I can't tell how much is from the new
kernel version, the new kde updates and from PAE.  In any event, I am a
happy camper.

Thanks for the replies.

[linux guy]

On Tue, 2009-09-29 at 20:23 -0700, Kam Leo wrote:
> On Tue, Sep 29, 2009 at 7:27 PM, Linuxguy123  wrote:
> > My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> > want to upgrade to 8 GB of RAM.
> >
> > I am currently using a 32 bit non PAE kernel.  How do I change to using
> > a PAE kernel ?
>
> yum install kernel-PAE
>
> Note: There may be additional packages which need to be installed,
> e.g. kernel-PAE-devel, kmod-nvidia-PAE, etc.
>
> I'm surprised that Anaconda did not detect that your processor was an
> i686 and automatically install the PAE kernel.
> > What difference in speed will I notice in doing this ?

Evolution seems to be faster, but 'free -m' isn't showing that I am
running out of memory or anything.   I generally have ~1600 MB free now.
I gained 1 GB, so before it would have been ~400 MB free.

Now I should increase the size of my swap file partition from 2GB to
4GB...

[Steven W. Orr]

On 09/30/09 00:21, quoth Linuxguy123:
> > > What difference in speed will I notice in doing this ?
>
> Evolution seems to be faster, but 'free -m' isn't showing that I am
> running out of memory or anything.   I generally have ~1600 MB free now.
> I gained 1 GB, so before it would have been ~400 MB free.
>
> Now I should increase the size of my swap file partition from 2GB to
> 4GB...

I just did this last week. Works fine. But I just have one question:

You say your situation is that you're now running at around 1.6G free mem. So
why bump the swap area? You can do it, but the whole point was to use more
memory. If you didn't run out of swap before then you're even less likely to
run out now, unless you now plan on doing things that you didn't do before.

[linux guy]

On Wed, 2009-09-30 at 00:43 -0400, Steven W. Orr wrote:
> On 09/30/09 00:21, quoth Linuxguy123:
> > > > What difference in speed will I notice in doing this ?
> >
> > Evolution seems to be faster, but 'free -m' isn't showing that I am
> > running out of memory or anything.   I generally have ~1600 MB free now.
> > I gained 1 GB, so before it would have been ~400 MB free.
> >
> > Now I should increase the size of my swap file partition from 2GB to
> > 4GB...
>
> I just did this last week. Works fine. But I just have one question:
>
> You say your situation is that you're now running at around 1.6G free mem. So
> why bump the swap area? You can do it, but the whole point was to use more
> memory. If you didn't run out of swap before then you're even less likely to
> run out now, unless you now plan on doing things that you didn't do before.

I'm running 1.6 GB free when not running any of my heavy duty
applications like ufraw (batch), digikam, eclipse (sometimes 2 or more
instances), gimp, a couple browsers, evolution and a couple Open Office
apps.

Did I mention that I want to start editing HD video ?

I need 8 GB of RAM !

BTW: The PAE kernel seems to run faster.

[Steven W. Orr]

On 09/30/09 01:27, quoth Linuxguy123:
> On Wed, 2009-09-30 at 00:43 -0400, Steven W. Orr wrote:
> > On 09/30/09 00:21, quoth Linuxguy123:
> > > > > What difference in speed will I notice in doing this ?
> > >
> > > Evolution seems to be faster, but 'free -m' isn't showing that I am
> > > running out of memory or anything.   I generally have ~1600 MB free now.
> > > I gained 1 GB, so before it would have been ~400 MB free.
> > >
> > > Now I should increase the size of my swap file partition from 2GB to
> > > 4GB...
> >
> > I just did this last week. Works fine. But I just have one question:
> >
> > You say your situation is that you're now running at around 1.6G free mem. So
> > why bump the swap area? You can do it, but the whole point was to use more
> > memory. If you didn't run out of swap before then you're even less likely to
> > run out now, unless you now plan on doing things that you didn't do before.
>
> I'm running 1.6 GB free when not running any of my heavy duty
> applications like ufraw (batch), digikam, eclipse (sometimes 2 or more
> instances), gimp, a couple browsers, evolution and a couple Open Office
> apps.
>
> Did I mention that I want to start editing HD video ?
>
> I need 8 GB of RAM !
>
> BTW: The PAE kernel seems to run faster.

I seriously doubt that the PAE kernel is running faster. If anything, I would
suspect it of running slower because of the added overhead of a page table
algorithm that now handles a larger address space than it did before. I could
very well be wrong since I have not looked at what the PAE kernel actually does.

My point is that people who think something is faster by using the
non-scientific touchy-feely method are the same people who get brain cancer
from cell phones. If you didn't take measurements before adding the extra RAM
 with the old non-PAE kernel, then you have no basis for commenting on
performance improvement. Change one thing and measure each time. That's the
only way. In your case you added RAM and then changed the kernel to PAE to be
able to access all of the new RAM. Since register to register access is about
~1ns, and register to memory access is about ~10ns, and a disk access is
around ~10ms, then any extra ram you throw at a problem may end with a speed
increase of up to ~>700 times. You didn't actually take *any* measurements so
you really have no basis for saying that a PAE kernel is faster than a non-PAE
kernel. If you really want to tell if it is then you need to boot with a
non-PAE kernel and try to do something in less than 3.2G of ram that doesn't
access the disk and then run the same test with a PAE kernel with no added ram.

And we're all above average in bed too. ;-)

[Bill Davidsen]

Linuxguy123 wrote:
> On Wed, 2009-09-30 at 00:43 -0400, Steven W. Orr wrote:
> > On 09/30/09 00:21, quoth Linuxguy123:
> > > > > What difference in speed will I notice in doing this ?
> > >
> > > Evolution seems to be faster, but 'free -m' isn't showing that I am
> > > running out of memory or anything.   I generally have ~1600 MB free now.
> > > I gained 1 GB, so before it would have been ~400 MB free.
> > >
> > > Now I should increase the size of my swap file partition from 2GB to
> > > 4GB...
> >
> > I just did this last week. Works fine. But I just have one question:
> >
> > You say your situation is that you're now running at around 1.6G free mem. So
> > why bump the swap area? You can do it, but the whole point was to use more
> > memory. If you didn't run out of swap before then you're even less likely to
> > run out now, unless you now plan on doing things that you didn't do before.
>
> I'm running 1.6 GB free when not running any of my heavy duty
> applications like ufraw (batch), digikam, eclipse (sometimes 2 or more
> instances), gimp, a couple browsers, evolution and a couple Open Office
> apps.
>
> Did I mention that I want to start editing HD video ?

Which program are you using (planning to use)?
> I need 8 GB of RAM !
>
> BTW: The PAE kernel seems to run faster.

Having extra memory certainly make things run faster, the actual CPU is some 
tiny bit slower when doing context switches and on cache misses. You can measure 
the CPU effect, you can *feel* the boost from the extra memory.

[Craig White]

On Tue, 2009-09-29 at 20:23 -0700, Kam Leo wrote:
> On Tue, Sep 29, 2009 at 7:27 PM, Linuxguy123  wrote:
> > My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> > want to upgrade to 8 GB of RAM.
> >
> > I am currently using a 32 bit non PAE kernel.  How do I change to using
> > a PAE kernel ?
>
> yum install kernel-PAE
>
> Note: There may be additional packages which need to be installed,
> e.g. kernel-PAE-devel, kmod-nvidia-PAE, etc.
>
> I'm surprised that Anaconda did not detect that your processor was an
> i686 and automatically install the PAE kernel.

----
I think anaconda on F11 would recognize and install PAE kernel but OP
has continually upgraded from F8 through to F11 and that probably is why
he didn't automatically get the PAE kernel installed.

Craig

[Kam Leo]

On Tue, Sep 29, 2009 at 9:21 PM, Craig White  wrote:
> On Tue, 2009-09-29 at 20:23 -0700, Kam Leo wrote:
> > On Tue, Sep 29, 2009 at 7:27 PM, Linuxguy123  wrote:
> > > My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> > > want to upgrade to 8 GB of RAM.
> > >
> > > I am currently using a 32 bit non PAE kernel.  How do I change to using
> > > a PAE kernel ?
> >
> > yum install kernel-PAE
> >
> > Note: There may be additional packages which need to be installed,
> > e.g. kernel-PAE-devel, kmod-nvidia-PAE, etc.
> >
> > I'm surprised that Anaconda did not detect that your processor was an
> > i686 and automatically install the PAE kernel.
>
> I think anaconda on F11 would recognize and install PAE kernel but OP
> has continually upgraded from F8 through to F11 and that probably is why
> he didn't automatically get the PAE kernel installed.

I also upgraded one of my systems all the way from F8 to F11. It only
has 512 MB of RAM and PAE was installed.
> Craig

[Ambrogio]

Il giorno mar, 29/09/2009 alle 20.23 -0700, Kam Leo ha scritto:
> I'm surprised that Anaconda did not detect that your processor was an
> i686 and automatically install the PAE kernel.

I was surprised too when I made upgrade from Fedora 9 (with only PAE
kernel) to Fedora 10 using preupgrade.
After the boot everytime I had an error message for package not found.

I understand trying and trying that anaconda boot with a kernel without
PAE, but preupgrade download only the PAE.
So no upgrade can start.

I solved it installing the right kernel on my fedora 9 and running
preupgrade. After that I removed the i586 kernel.

I hope it was solved on Fedora 11, because I will do the preupgrade also
from Fedora 10 to Fedora 11

Bye
 Ambrogio

[Suresh Danda]

*But Exact my question is why its is detecting IDE hard disk as sda.......?*

On Wed, Sep 30, 2009 at 12:46 PM, Ambrogio  wrote:
> Il giorno mar, 29/09/2009 alle 20.23 -0700, Kam Leo ha scritto:
> > I'm surprised that Anaconda did not detect that your processor was an
> > i686 and automatically install the PAE kernel.
>
> I was surprised too when I made upgrade from Fedora 9 (with only PAE
> kernel) to Fedora 10 using preupgrade.
> After the boot everytime I had an error message for package not found.
>
> I understand trying and trying that anaconda boot with a kernel without
> PAE, but preupgrade download only the PAE.
> So no upgrade can start.
>
> I solved it installing the right kernel on my fedora 9 and running
> preupgrade. After that I removed the i586 kernel.
>
> I hope it was solved on Fedora 11, because I will do the preupgrade also
> from Fedora 10 to Fedora 11
>
> Bye
>  Ambrogio
>
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[Rahul Sundaram]

On 09/30/2009 01:30 PM, Suresh Danda wrote:
> *But Exact my question is why its is detecting IDE hard disk as sda.......?*

Linux kernel in recent versions use the scsi layer even for IDE hard
disks.  Fedora from version 7 has inherited this behaviour

http://fedoraproject.org/wiki/Fedora7/FAQ#Why_are_all_the_hard_disks_in_my_s...

Rahul

Ps: Please post mails as plain text here instead of HTML

[Bruno Wolff III]

On Wed, Sep 30, 2009 at 13:30:06 +0530,
  Suresh Danda  wrote:
> *But Exact my question is why its is detecting IDE hard disk as sda.......?*

Around Fedora 7 the driver for handling PATA disks changed to libata, which
uses sd names for devices.

If you really need hd names, there is probably a way to do this with udev.

[Phil Meyer]

On 09/29/2009 08:27 PM, Linuxguy123 wrote:
> My laptop has 4GB of RAM. It is currently using only 3 GB of RAM.  I
> want to upgrade to 8 GB of RAM.
>
> I am currently using a 32 bit non PAE kernel.  How do I change to using
> a PAE kernel ?
>
> What difference in speed will I notice in doing this ?
>
> Thanks

Think of dual port memory like striped disks on a super fast 
controller.  Performance is doubled.

Think of a PAE kernel as concatenating each memory stick.  Each read to 
N+1 must read THROUGH 1.  It is slower, but not twice as slow.

This is a gross oversimplification, but the principle is correct.

The fact remains, that memory reads above the PAE watermark will be slower.

The fact remains that kernel, application, and user memory reside below 
most caches, meaning that your cache buffers may suffer slightly, but 
its still way faster than reads to disk.  It also means that if you plan 
to run a very large application space above 3GB, you should really move 
to 64 bit.  That is what it was designed for.

PAE is/was intended as a (truly miraculous) stopgap measure until users 
are able to move to 64bit.  Only MS dragging of their feet has prevented 
this move from happening many many years ago.

Every other CPU arch used in general computing moved to 64 bit in the 
early nineties (SPARC, HP, IBM, etc).  In fact, HP bet the CPU bank on 
Titanium, and because MS backed out (They couldn't get Windows Server to 
stabilize on it, and if you ever tried 64 bit XP then you already know 
what happened there), HP lost the whole game.  Think about it.

Once again, I am not trying to rewrite history, just offering some 
google fodder for ya if yer interested.

Good Luck!