stosss wrote:
> If I compile the kernel with 64GB instead of 4GB on a 32-bit system
> that would allow me to use more than 4GB of physical RAM. Is my
> understanding correct?
Maybe. It depends on your hardware. If it's supported in HW, the
kernel will do the equivalent of changing segments when it needs to
address memory outside of the current 32-bit logical address. Of course
this is not very efficient.
> I have seen earlier that 64-bit does not improve performance very much
> over 32-bit. My main interest in building a 64-bit system is to be
> able to access more physical RAM. Will I be able to accomplish my
> objective with the 64GB switch instead of the 4GB switch in the kernel
> configuration?
If you are using more than 4G at one time, you will see an improvement.
Personally, I have 2G on my main system and it almost never swaps, so
it wouldn't make much difference.
OTOH, a large server may need it. For example:
$ free
total used free shared buffers cached
Mem: 8068444 7991296 77148 0 40 4596364
-/+ buffers/cache: 3394892 4673552
Swap: 7812492 1190780 6621712
> Is there any other advantage to using a 64-bit system instead of a
> 32-bit system?
It really depends on your application. If you are doing a simulation of
a complex fluid flow problem, it may be useful. If you are browsing the
web, probably not.
-- Bruce
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