32Bit vs 64Bit

32Bit vs 64Bit

[regatta]

Hi everyone,

I have a question about the 64Bit mode in AMD 64bit

My question is if I run a 32Bit application in Optreon AMD 64Bit with
Linux 64Bit does this give my any benefit ? I mean running 32Bit
application in 64Bit machine with 64 Linux is it better that running
it in 32Bit or doesn't make any different at all ?

Thanks
-- 
Best Regards,
--------------------
-*- If Linux doesn't have the solution, you have the wrong problem -*-

Re: 32Bit vs 64Bit

[Eric Dumazet]

regatta wrote:

> Hi everyone,
> 
> I have a question about the 64Bit mode in AMD 64bit
> 
> My question is if I run a 32Bit application in Optreon AMD 64Bit with
> Linux 64Bit does this give my any benefit ? I mean running 32Bit
> application in 64Bit machine with 64 Linux is it better that running
> it in 32Bit or doesn't make any different at all ?
> 
> Thanks

Hi

Running a 32 bits application on a x86_64 kernel gives more virtual 
address : 4GB of user memory, instead of 3GB on a standard 32bits kernel

If your application uses a lot of in-kernel ressources (like tcp 
sockets and network buffers), it also wont be constrained by the 
pressure a 32 bits kernel has on lowmem (typically 896 MB of lowmem)

If your machine has less than 2GB, running a 64bits kernel is not a 
win, because all kernel data use more ram (pointers are 64 bits 
instead of 32bits)

Eric

Re: 32Bit vs 64Bit

[regatta]

My question because We ran a 32 Bit application in Sun AMD64 Optreon
with 1GB connection (Kernel 2.4 x86_64 with 8 Gb memory & 2 CPUs)  and
we had trouble time with it because the user tried to put the
application processing data in a nas box (in the network) and that
made the machine to use more than 60% of the NAS CPU and no one else
was able to access the NAS

right now we are trying to see if the problem because the AMD64 Bit is
very powerful or  is it because it has 1GB connection and the
application designed to be a bad :)




On Wed, 16 Mar 2005 16:59:15 +0100, Eric Dumazet <dada1@cosmosbay.com> wrote:
> regatta wrote:
> 
> > Hi everyone,
> >
> > I have a question about the 64Bit mode in AMD 64bit
> >
> > My question is if I run a 32Bit application in Optreon AMD 64Bit with
> > Linux 64Bit does this give my any benefit ? I mean running 32Bit
> > application in 64Bit machine with 64 Linux is it better that running
> > it in 32Bit or doesn't make any different at all ?
> >
> > Thanks
> 
> Hi
> 
> Running a 32 bits application on a x86_64 kernel gives more virtual
> address : 4GB of user memory, instead of 3GB on a standard 32bits kernel
> 
> If your application uses a lot of in-kernel ressources (like tcp
> sockets and network buffers), it also wont be constrained by the
> pressure a 32 bits kernel has on lowmem (typically 896 MB of lowmem)
> 
> If your machine has less than 2GB, running a 64bits kernel is not a
> win, because all kernel data use more ram (pointers are 64 bits
> instead of 32bits)
> 
> Eric
> 
> 


-- 
Best Regards,
--------------------
-*- If Linux doesn't have the solution, you have the wrong problem -*-

Re: 32Bit vs 64Bit

[peto]

regatta wrote:

>Hi everyone,
>
>I have a question about the 64Bit mode in AMD 64bit
>
>My question is if I run a 32Bit application in Optreon AMD 64Bit with
>Linux 64Bit does this give my any benefit ? I mean running 32Bit
>application in 64Bit machine with 64 Linux is it better that running
>it in 32Bit or doesn't make any different at all ?
>  
>
It differs on type of the  appliction you used. measured values in Linux
shows that x86-64 64 bit app+OS+CPU have performance from 120% to 500% 
of the performance of the 32 bit conterpart

in MS OS it is x86-64   as 80%-190% of the 32 bit MS OS

It is because pointer manipultaion takes longer time because of higer 
width od the 64 bit pointers but 64 bit multiplication is 6 times faster 
no x86-64 system then in 32 bit system and in Windows there is tragic 
memory management tak causes higher pointer manipulation. But there are 
pracitcaly no anothere performance differency in both architectures


Yours faithfuly
Peter Fodrek

Re: 32Bit vs 64Bit

[Helge Hafting]

On Wed, Mar 16, 2005 at 06:44:51PM +0300, regatta wrote:
> Hi everyone,
> 
> I have a question about the 64Bit mode in AMD 64bit
> 
> My question is if I run a 32Bit application in Optreon AMD 64Bit with
> Linux 64Bit does this give my any benefit ? I mean running 32Bit
> application in 64Bit machine with 64 Linux is it better that running
> it in 32Bit or doesn't make any different at all ?
> 
There are quite a few indirect benefits:

The kernel itself might be faster because it takes advantage
of extra registers and so on.  So the app might wait less on
its syscalls.

Also, this app may be 32-bit but surely a lot of other programs
will be available as 64-bit software and will be faster.  That
leaves more time for running your 32-bit app.

Helge Hafting

Re: 32Bit vs 64Bit

[Bodo Eggert]

regatta <regatta@gmail.com> wrote:

> My question because We ran a 32 Bit application in Sun AMD64 Optreon
> with 1GB connection (Kernel 2.4 x86_64 with 8 Gb memory & 2 CPUs)  and
> we had trouble time with it because the user tried to put the
> application processing data in a nas box (in the network) and that
> made the machine to use more than 60% of the NAS CPU and no one else
> was able to access the NAS

Does the application happen to frequently access the data in small chunks
randomly scatterd across the file(s)?