Fedora 9 32 or 64 Bit - Which One?

Alan Cox alan at lxorguk.ukuu.org.uk
Mon Oct 27 16:14:18 UTC 2008


On Mon, 27 Oct 2008 11:54:47 -0400
Matthew Flaschen <matthew.flaschen at gatech.edu> wrote:

> Alan Cox wrote:
> 
> > The moment you have more than about 900MB of RAM there are big advantages
> > to running a 64bit kernel as it can keep all of physical and virtual
> > space mapped at the same time, which is a big performance win.
> > 
> > Alan
> 
> Can you point to any benchmarks showing a significant performance gain
> for a 1 GB desktop user?

I'm not aware of anyone having sat down and run formal benchmarks on the
Fedora desktop. One of the problems with that is that you need a
reproducable representative benchmark typically scripting all the mouse
clicks and keypresses, using identical data sets and so on. They are hard
to produce and I'm not aware of any Linux ones that don't involve payment
of large sums of money to third party who runs their own closed secret
test and produces a number you can stick up in lights. So let me turn the
question around - given that the evidence from microbenchmarks and CPU
architects is that 64bit is the better choice can you show any
good quality benchmarks showing it isn't a win ?

There are real benchmark numbers for CPU performance, relative code
density and the like and you can generate mapping cost benchmarks. AMD
and Intel have published various studies on the former two. There are
lots of benchmarks for server performance because there is money in that
market so people actually TPC and other things to sell enterprise product.

However if you cared about performance you wouldn't be running Gnome or
Kde ;)

Alan




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