
Troubled Times Ahead for Supercomputers - baazaar
http://www.ecnmag.com/news/2016/04/troubled-times-ahead-supercomputers
======
justinalanbass
The Green 500 is more than a concern for global warming. It is also a measure
of scalability due to heat dissipation and power supply concerns. The
difficulty of achieving a human-brain sized supercomputer will be more about
energy efficiency than actual computational ability.

------
petschge
Actually a problem few people are aware of and are working on is the problem
of IO. While there is the old quip of supercomputers being devices to turn CPU
bound problems into IO bound problems, it is a real problem to keep a well
tuned HPC application on a supercomputer fed with data. And even if you are
lucky and have an application with with a small input dataset, it gets hard to
write snapshots (e.g. for checkpointing) once you go beyond 100000 CPUs or so.
And at that point you really want checkpointing, because the failure
probabilty of the nodes rears it's ugly head.

------
cmiller1
>The ratio can now be as much as 1:100, so a supercomputer is forced to spend
the vast majority of its time moving data to and from memory. This is spurring
the adoption of data-tiering hardware and software that try to maximize CPU
effectiveness by storing frequently accessed data in high-speed tiers such as
solid-state drive

Err... this isn't new, wouldn't the high speed tiers be processor registers
and cache and we've been doing this for over 30 years?

~~~
kirrent
Absolutely it's nothing new, it's just a case of the scale of the problem
being larger than ever. IO speed increases haven't kept up with floating
operation performance of processors. If you're performing operations on a
large, distributed dataset it's easier than ever to have your processor be
data starved. Of course, that's why any decent HPC system will include high
speed local data stores such as an SSD and plenty of RAM. That's why cache
size on these processors is important. That's why systems are more
heterogeneous than ever.

I feel like some writers in HPC (ironically) miss the free lunch of faster and
faster systems with not much extra effort. With more complexity in your
supercomputer comes more power and more difficulty in writing software. That's
unavoidable.

------
Jgrubb
Trying to figure out why the menu is borked on the iPhone. If you reload the
article in landscape it works. Sorry!

