[LAU] Bye Bye 32 bit

[Jeremy Henty]

Paul Davis wrote:

> On Thu, Dec 28, 2017 at 2:11 PM, Jeremy Henty <onepoint at starurchin.org>
> wrote:
> 
> > Will Godfrey wrote:
> >
> > > If I've understood that correctly you  can also ensure that they are
> > > also on the same socket, which apparently improves memory access.
> >
> > I think  this is what  is meant  by NUMA (Non-Uniform  Memory access).
> 
> ​AFAIK, NUMA is dead for everything except a few research systems.
> 
> Parallel/multi-processor systems these days are all "symmetric" (all
> processors have symmetrical access to all memory).
> 
> NUMA  is  really, really,  really  hard  to  get right.  Why?  Cache
> invalidation.    Several   companies,   organizations,   etc.   have
> tried. Last time I looked (and it  has been a while, but I was quite
> involved with this stuff in the mid 1990s), everybody failed.​

Until I  read the Wikipedia NUMA  page just now I  didn't realise that
NUMA involved multiple processors having  their own caches of the same
data.  Thanks for bringing me up to speed.

Regards,

Jeremy Henty