Message-ID: <423857D3.80609@cosmosbay.com>
Date: Wed, 16 Mar 2005 16:59:15 +0100
From: Eric Dumazet <dada1@cosmosbay.com>
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To: regatta <regatta@gmail.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: 32Bit vs 64Bit
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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

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