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Old 07-22-2010, 10:15 PM
JohnS
 
Default To PAE or not to PAE...

On Thu, 2010-07-22 at 17:55 -0400, ken wrote:
> On 07/22/2010 05:43 PM JohnS wrote:
I'm trying to catch up...

Is the 737M cached (in the output above) what is reserved for bios or
chipset...? and what is gained back through remapping?


---
The 737 is for Programs and Applications use and not for BIOS or
Chipsets.

John

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Old 07-22-2010, 10:17 PM
Hakan Koseoglu
 
Default To PAE or not to PAE...

On 22/07/10 22:33, ken wrote:

> Is the 737M cached (in the output above) what is reserved for bios or
> chipset...? and what is gained back through remapping?
Nope, it simply means even if I had 2GB RAM, there'd be plenty I'm not
using for anything but cache - I don't do much on this laptop but
browsing these days

What we are suffering from is explained neatly here:
http://en.wikipedia.org/wiki/PCI_hole

Simply put, if the BIOS+chipset does not support mapping these reserved
areas to higher addresses this memory is lost to us.

My Dell Inspiron 9400 is about 3+ years old now. More recent hardware
have the necessary bits and pieces so that you can see all 4GB and use
it with 64 bit or 32 bit + PAE. Server chipsets had this kind of support
even earlier. Unfortunately for mine, Dell decided to only support 3GB.
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Old 07-22-2010, 10:42 PM
Hakan Koseoglu
 
Default To PAE or not to PAE...

Hi John,
On 22/07/10 19:56, JohnS wrote:
> Try about 69Gbytes& What are you fiddling with? limits.conf?
I think you read my mail too quickly and wrote a reply in similar speed.
So did I read the original post too quickly and didn't realise he was
complaining about the memory hole...

You're right to say PAE goes to 64GB although in the past various
distros had kernels compiled for different max addresses for various
reasons.
4GB address space still applies to 32 bit apps. To use more than 4GB
tricks as such
(http://www.puschitz.com/TuningLinuxForOracle.shtml#ConfiguringVeryLargeMem ory)
need to be used.
I haven't had to use these kinds of tricks for years since every machine
I encounter has 64 bits and Oracle runs nicely on them perfectly happily.

I miss reading through Puschitz's tips & tricks. Lately all Oracle
versions run pretty much out of the box on CentOS/Upstream. No sense of
satisfaction from seeing it running after battling with it for hours.
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Old 07-22-2010, 11:17 PM
JohnS
 
Default To PAE or not to PAE...

On Thu, 2010-07-22 at 23:42 +0100, Hakan Koseoglu wrote:
> Hi John,
> On 22/07/10 19:56, JohnS wrote:
> > Try about 69Gbytes& What are you fiddling with? limits.conf?
> I think you read my mail too quickly and wrote a reply in similar speed.
> So did I read the original post too quickly and didn't realise he was
> complaining about the memory hole...
>
> You're right to say PAE goes to 64GB although in the past various
> distros had kernels compiled for different max addresses for various
> reasons.
> 4GB address space still applies to 32 bit apps. To use more than 4GB
> tricks as such
> (http://www.puschitz.com/TuningLinuxForOracle.shtml#ConfiguringVeryLargeMem ory)
> need to be used.
> I haven't had to use these kinds of tricks for years since every machine
> I encounter has 64 bits and Oracle runs nicely on them perfectly happily.
>
> I miss reading through Puschitz's tips & tricks. Lately all Oracle
> versions run pretty much out of the box on CentOS/Upstream. No sense of
> satisfaction from seeing it running after battling with it for hours.
> _---
LOL yea 64 is correct. I said 69. See my post earlier...

John

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Old 07-23-2010, 10:21 AM
John Doe
 
Default To PAE or not to PAE...

From: Hakan Koseoglu <hakan@koseoglu.org>

> > In the past, I heard that these 700MB were normally reserved for bios or
>chipset
> It still is, even with with 64 bit. If your motherboard supports
> remapping this memory with 64 bit you can use the whole 4GB. Otherwise
> you're limited to 3.2:
>
> hakan@photon:~$ free -m
> total used free shared buffers cached
> Mem: 3262 1972 1290 0 103 737
> -/+ buffers/cache: 1131 2131
> Swap: 7812 308 7504
> hakan@photon:~$ arch
> x86_64

Thx for all the answers.
As a matter of fact, while my Dell Vostro 410 was getting 3.3GB without PAE,
a new Vostro 430 was getting only 3GB (but a full 4GB in PAE)...
I went anyway for the non PAE just for peace of mind and because 3GB is still
plenty.

Thx,
JD



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Old 04-16-2011, 03:31 PM
Kai Schaetzl
 
Default To PAE or not to PAE...

John Doe wrote on Thu, 22 Jul 2010 02:25:13 -0700 (PDT):

> And that running in PAE would slow down some processes.

The overhead is minimal, if you want those extra 700 MB, do it.

Kai


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