[OpenIndiana-discuss] oracle removes 32bit x86 cpu support for solaris 11 will OI do same?

[Steve Gonczi]

For Intel CPUs, 32 bit code is certainly more compact , and in some cases 
arguably faster than 64 bit code. (say, comparing the same code on the same machine 
compiled 32 and 64 bit) 

But, newer cpu silicon tends to make performance improvements 
in many ways (e.g locating more supporting circuity on the cpu's silicon, increasing L1 /L2 
cache sizes, etc) 

Newer CPUs also tend to be more energy efficient. 
Intel made great strides towards energy efficiency. 
E.g.: idling the cpu when not in use ( deep C states etc. 
of gating off any circuitry that is not in use, modulating the cpu clock rate 
( SpeedStep). 

So performance and energy efficiency is more dependent on 
which generation of cpu core design we have, rather than on 
just the the bitness . 


The primary advantage of "64 bit" per se ( ie running a given cpu in 64 bit mode) 
is the increased addressable memory space. 
The current hardware limit set by the manufacturers is at 48 address bits 
(256 terabytes theoretical limit) Actual OS support cuts this in half, or less. 
Motherboard limitations further curtail this, but 48G motherboards are now 
commonplace. 

On 32 bit Intel (Amd) you are typically limited to 4G, which is split between kernel and userland 
depending on the OS and configuration. (E.g.: 1G kernel and 3G userland) 

Steve 

----- "Michael Stapleton" <michael.stapleton at techsologic.com> wrote: 


While we are talking about 32 | 64 bit processes; 
Which one is better? 
Faster? 
More efficient? 

Mike 






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