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

It is not just about Erlang, but any language+runtime which has been designed upon a well-known set of sound principles (immutability, share-nothing, message-passing).

As long as order of evaluation does not matter (for a pure-functional code) some [major] parts of a program could be evaluated in parallel by runtime without any changes in the code (especially when a high-order function composition - map/filter/reduce/etc is the primary pattern). So, Haskell, for example, will do it too.

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

#5

Post by throwaway_yy2Di » Wed, Oct 22, 2014, 2:32 PM UTC

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?

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

#6

Post by vinkelhake » Wed, Oct 22, 2014, 2:33 PM UTC

dschiptsov wrote: post #4

It is not just about Erlang, but any language+runtime which has been designed upon a well-known set of sound principles (immutability, share-nothing, message-passing). As long as order of evaluation does not matter (for a pure-functional code) some [major] parts of a program could be evaluated in parallel by runtime without any changes in the code (especially when a high-order function composition - map/filter/reduce…

Haskell will do what? Automatic parallelization of code?

The big difference between Erlang and Haskell is that Erlang fundamentally encourages the programmer to think in terms of individual processes that communicate by message-passing. Programmers have also been taught that spawning processes is cheap so idiomatic Erlang code typically have tons of them.

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

#7

Post by jacques_chester » Wed, Oct 22, 2014, 2:39 PM UTC

For those as confused as I was at first, the critical line is "total time". 2.8s for the P8 vs 38.7s for the x86.

Otherwise the x86 comes out looking a lot better -- lower 95th percentile, lower max, lower average.

(Modulo usual complaints about benchmark porn: single run, lack of standard deviation, unknown configuration differences etc etc).

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

#8

Post by jacques_chester » Wed, Oct 22, 2014, 2:41 PM UTC

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?

> What is it good for?

Running very demanding single-system software. It's the sort of box you'd install DB2 or Oracle on, especially if you've already tied your business to IBM solutions in the past.

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

#9

Post by dragonwriter » Wed, Oct 22, 2014, 2:45 PM UTC

dschiptsov wrote: post #4

It is not just about Erlang, but any language+runtime which has been designed upon a well-known set of sound principles (immutability, share-nothing, message-passing). As long as order of evaluation does not matter (for a pure-functional code) some [major] parts of a program could be evaluated in parallel by runtime without any changes in the code (especially when a high-order function composition - map/filter/reduce…

> So, Haskell, for example, will do it too.

By "will do it" you mean "would, in theory, support a compiler that parallelized significant amounts of idiomatic code with no source changes"? Maybe. I don't think any existing Haskell compiler does that, though.

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

#10

Post by Marat_Dukhan » Wed, Oct 22, 2014, 2:54 PM UTC

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?

+ Hardware Transactional Memory that isn't buggy