On 28/05/2012 15:43, Andy Smith wrote:
> Hello,
>
> As you may be aware, BitFolk currently doesn't support 64-bit
> guests. The reasons for this are:
>
> - 64-bit is alleged to be a little slower and use more memory
> per-process compared to 32-bit.
> - 99.04% of BitFolk customers have less than 2GiB addressable RAM.
> - Supporting only 32-bit or only 64-bit is a bit simpler.
>
> We do, however occasionally lose custom due to not supporting 64-bit
> guests.
>
Another thought to throw in to the mix here is the x32 ABI, introduced
with linux 3.4: this essentially uses all of the architectural features
of x86-64 (thus gaining the benefit of the extra registers and other
improvements over vanilla x86-32), but uses 32-bit addressing. This
gives you much of the benefit of the x86-64 arch without the memory
overhead of 64-bit pointers, and is ideal for circumstances where the
32-bit address space is never going to be exceeded (e.g. the vast
majority of customer VPSes at present). As I understand it (i.e. correct
me if I'm wrong), the kernel itself would still be x86-64, so from a
hosting point of view guests would look & work exactly the same as
regular 64-bit guests.
OS support is some way off yet, for Debian we're probably looking at the
release after Wheezy (i.e. sometime in 2015), by which time the point
may be moot if there is a sufficient abundance of memory. That said,
even with a doubling of RAM I imagine there will still be a decent
proportion of customers with < 2GiB memory at that time for whom an x32
userspace might make sense.
--
Phil
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