IBM Mainframe Discussion List <IBM-MAIN@bama.ua.edu> wrote on 01/01/2010 07:27:20 PM: Mainframe Discussion List > > In article <listserv%201001011105537168.0...@bama.ua.edu> you wrote: > > On Fri, 1 Jan 2010 08:41:53 -0800, Edward Jaffe wrote: > > > > > >The z/OS RSM developers introduced functionality to allow Java to > > >acquire storage within the previously "thick" bar for performance reasons. > > > > > I would guess, economy in page and segment tables?
I was told that compressed pointers for storage below 32GB fit into a smaller space, so more compressed pointers fit in a cache line, leading to more effective cache utilization. Performance is all about the caches these days. I am not a Java person. I don't know what a compressed pointer is. > > I'm still intrigued that the (undocumented) option's name > > contains the substring "32G". Is 32GiB the size of a particular > > granule in 64-bit storage management? Or might the "32" refer > > to a fictitious "32-bit" addressing capability? > The range from 2GB to 32GB is set aside for a particular intended user, which is the JVM. > At some release 64-bit LE moved the CAA and other control blocks from > starting at 4G to 32G. I doubt that LE changed anything. Due to the RSM change, IARV64 is returning an address of 32GB instead of 4GB when LE creates the first memory object in the address space. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
