Lightningspeed haskell

[Ketil Malde]

Jan-Willem Maessen <jmaessen@mit.edu> writes:

> Absolutely.  Good high-level thread support trumps anything provided
> by the operating system.

Unless you have more than one CPU...

> Similar dramatic performance disparities have cropped up in the Java
> community.  There are Java benchmarks which create thousands of
> threads; most implementations slow to a crawl when this happens, as
> the operating system collapses under the crushing load.

In particular, Linux will have a problem with thousands of *runnable*
processes.  There's some potentially nasty O(>n) complexities when
processing the run queue, so while a couple of runnable processes is
very fast, having lots is not.  

In practice, most processes are blocked on IO most of the time, so
it seems it's only a problem for certain Java benchmarks.

-kzm
-- 
If I haven't seen further, it is by standing in the footprints of giants