Re: new software if moving to amd64?

2014-10-04 Thread Michael
Ray,

Well. Having done a lot of (kindly) support for older machines, i'd say leave 
the arch as is. While on the other hand it's fun to upgrade to a decent 
GNU/Linux version (a friend once said Linux is the greatest online adventure 
ever) so if you are bored, give it a shot :) but that does not imply to change 
the architecture.

The problem is just the 'fiddling' which consumes your time for nothing. Plus, 
multiarch (mixed i366 and amd64 packages) in reality is not that easily done as 
said. In my case, when i tried to set up google earth 32 bit (in a native 64bit 
env), it finally ends up to move most (or all?) of the installation to 32 bit. 
Well, it still works, but at least looks ugly in the package manager :) and i'm 
sure the respective package dependencies could be resolved differently, but i 
won't blame the maintainers. It's just a lot of work, on all ends, to make it 
real, and the tiny word 'work' resembles the huge problem, paid or not.

There is one feature of Windows  7 that struck me though i did not really dive 
into it ... when a software does not launch or work properly, the Windows OS 
tries to identify and solve the problem, for example by switching to 'Windows 
XP mode' where 32 bit apps run in an emulation environment. Maybe they chose 
the safe bet, i can't tell, especially since Windows always makes a big fuzz 
over solutions to problems that should not exist in the first place.
http://windows.microsoft.com/en-us/windows7/understanding-hardware-and-software-for-64-bit-windows

Our friendly competitor have a not so bad overview for beginners on these pages
http://windows.microsoft.com/en-us/windows7/taking-the-mystery-out-of-64-bit-windows

There are very few GNU/Linux apps which in the past were available only in 32 
bit packages, proprietary things like google-earth and maybe skype, meaning 
you'd need the debian multiarch feature. Meanwhile those issues could or should 
be solved, but still, there's no guarantee since those the props usually do not 
have significant GNU/Linux support on their end. Yet i'm running googleearth 
right now and the debian maintainer even tries to upgrade to ge7.
https://plus.google.com/+AdnanHodzic/posts/g2JyQ93ej51

As for the gain of 64 vs 32 bit, one should ask how urgent are high performance 
tasks on the respective computer. This is not totally trivial even if you're 
only doing some office and internet, because most people at least want smooth 
movies and a graphical desktop. Besides the CPU, also the GPU is involved. I 
imagine that typical GPU tasks involve massive parallel computing and other 
stuff that possibly could profit from 64bit. Please don't nail me down on this, 
i really don't know much about, but i wonder if the 32/64 bit question is just 
the same for GPUs. Maybe someone can enlighten me.
ps. It seems there is http://www.nvidia.com/object/feature_64-bit.html

micha





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Re: new software if moving to amd64?

2014-10-04 Thread Lennart Sorensen
On Fri, Oct 03, 2014 at 02:45:59PM -0700, Ray Andrews wrote:
 Ok thanks, that's a good start right there.  Looking at various
 blogs and such, it seems no two people can agree if the conversion
 to '64 is beneficial or even wise.  I have only 2 GB of RAM on this
 machine, so that's no motive.  I hear talk of various problems on
 the one hand, vs. claims of better performance on the other.  Can I
 sorta slide from '32 to '64 by degrees? I mean, so that whenever I
 do an upgrade it will convert what's convertible while leaving the
 rest of the system '32?  Or should I start afresh? Or should  I just
 leave this older machine alone?

64bit has twice the registers than 32bit in the case of x86, so some
programs gain some performance that way.  Also 64bit always uses SSE for
floating point, while 32bit by default uses x87 floating point which is
a lot slower.

Now 64bit does have some overhead due to the pointers being twice as big,
which means more cache use and memory bandwidth, although probably not
that much in general.

The best option will actually end up being x32 (which is 32bit programs
using the 64bit cpu so you get all the new registers and SSE floating
point, but without the pointer overhead).  Not sure how far along x32
is at this point.

-- 
Len Sorensen


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