Re: iozone reality check: was zam, please discuss this

[Hans Reiser <reiser@namesys.com>]

George Beshers wrote:

>
> Caveat: I have not looked at the iozone test so this is purely in 
> response
> to Han's description.
>
> The examples I know of are apps that allocate an mmap'd area for garbage
> collection: ocaml, sml-nj, and I believe ghc (Haskell) do this.  While 
> these
> systems usually have generational GCs at some point major collections
> happen and then I *believe* that you will see lots of dirty pages.
>
> Note: the 'believe' is based on some experiments on an SGI ccNuma
> system with profiling tools---I was looking at local access issues and
> noticed the pattern of changes to flag objects as "marked" in a 
> mark/sweep
> collector.  I then tried ocaml as an experiment and saw something
> similar.
>
>
> I have not look at Boehm conservative collector in some time, but if
> memory serves me correctly it uses separate arrays to hold the bits;
> using mmap is an option---I don't know if it is in common use.
>
> Some 18-20 months ago I spent some time looking at the Java GC
> but I don't remember its using mmap() and I no longer have the source
> available.
>
> George Besher

When you say lots, do you mean close to or more than physical ram?