Erlang and IBM Power8 in the cloud: super-high single-system parallelism • Hacker News Board

Re: Erlang and IBM Power8 in the cloud: super-high single-system parallelism

#61

Post by saosebastiao » Thu, Oct 23, 2014, 6:53 AM UTC

coolsunglasses wrote: post #55

felixgallo wrote: post #50

Earlier quoted context omitted.

I love my haskell brethren dearly, but haskell isn't organized structurally around an essentially-mandatory fundamentally concurrent, debuggable, quasi-preemptive core like OTP. Not that it won't get there eventually (cf. Cloud Haskell) but it's more than just being able to run concurrent threads. Note: this is not a language flame, just a personal opinion/observation, and I love and welcome correction.

Haskellers like to pick and choose their abstractions. That's why we have MVar and TVar (STM) and IVar and locks/semaphores and unbounded channels and bounded channels and software transactional channels and green threads and Async and OS threads… You're going to see what Erlang did atomized, implemented piecemeal, and reconstructed. Cloud Haskell burnt too much goodwill in pursuit of a mostly pointless feature. That…

Let us know when you get to 9-nines on a distributed application.

Re: Erlang and IBM Power8 in the cloud: super-high single-system parallelism

#62

Post by [deleted] » Thu, Oct 23, 2014, 3:24 PM UTC

apaprocki wrote: post #58

wmf wrote: post #56

Earlier quoted context omitted.

I would assume that the IBM JVM uses DFP instructions to implement the BigDecimal class .

Yes, according to IBM's presentations, BigDecimal in their JVM uses 64-bit DFP instructions on their hardware. Minimum hardware level is POWER6 or Z10 (Z9 supported via microcode). http://www.ibm.com/developerworks/rational/cafe/docBodyAttac...

[deleted]

Re: Erlang and IBM Power8 in the cloud: super-high single-system parallelism

#63

Post by wmf » Fri, Oct 24, 2014, 1:48 AM UTC

apaprocki wrote: post #60

throwaway_yy2Di wrote: post #5

How does POWER8 compare to x86, e.g. Haswell? Just skimming some of the architecture details... * 4x hardware threads per core (8-way SMT vs. 2) * 1/4th FP throughput per core (8 SP flops/cycle vs. 32) * 3x bandwidth to RAM (230 GB/s vs. 68) [edit: updated for Haswell-EP] https://en.wikipedia.org/wiki/POWER8#Specifications http://www.redbooks.ibm.com/abstracts/tips1153.html What is it good for?

Curious aside -- is there any blog / article out there where someone has tried to max out network bandwidth on an x86 box? I checked a POWER8 we have today and it has 14 PCIe3 slots (mix of 8x/16x), so theoretically one could load up 14 40GbE NICs on it. I'd be interested to see some kind of I/O shootout to see where both systems hit a wall. e.g. Snabb Switch 20x10GbE on x86 https://lukego.github.io/blog/2013/06/23/e…

I have some x86 servers with seven slots and 14 10G ports, but we only managed to get 8 ports working in netmap. Intel has done some crazy stuff with DPDK and I've seen a demo of over 300 Gbps on a 4S machine.

I've also seen some stuff on Power8 networking but it's not public.

Re: Erlang and IBM Power8 in the cloud: super-high single-system parallelism

#64

Post by dschiptsov » Fri, Oct 24, 2014, 12:48 PM UTC

felixgallo wrote: post #50

dschiptsov wrote: post #25

Earlier quoted context omitted.

Yes, indeed. Marlow's book is really good one.

I love my haskell brethren dearly, but haskell isn't organized structurally around an essentially-mandatory fundamentally concurrent, debuggable, quasi-preemptive core like OTP. Not that it won't get there eventually (cf. Cloud Haskell) but it's more than just being able to run concurrent threads. Note: this is not a language flame, just a personal opinion/observation, and I love and welcome correction.

You are right. Haskell is an academic research vehicle while Erlang is a pragmatic "industry-strength" (i hate these buzzwords, but they are useful generalizations) functional language.

In theory, we could re-write almost any part of OTP in Haskell, in practice, however, "runtime is hard" and the biggest selling point of Erlang is that its runtime and standard library (OTP) has been evolved for almost 20 years and is based on the same principles of a functional language (except, perhaps lazyness by default) as Haskell.

In other words, while Haskell is a "playground for researches of type theory in context of programming languages and compilers" Erlang/OT is a "telecom industry-standard toolkit".

A close analogy, in my opinion, could be the pair of Scheme/Racket and CL. The first was mostly an academic teaching and research tool, while second is a pragmatic (but unfortunately bloated) tool-set.