[HPADM] TR : [SUMMARY] 32/64 bit architectures

From: HAUTECOEUR Bruno (HAUTECOB_at_ESSILOR.fr)
Date: 07/08/04

  • Next message: Rita Workman: "[HPADM] 32/64 bit architecture-Att-Mr. Hassell" 
    To: hpadm <hpux-admin@dutchworks.nl>
Date: Thu, 8 Jul 2004 11:44:25 +0200

    Thanks one more time to Bill ;-)
     
    -----Message d'origine-----
    De : Bill Hassell [mailto:bill@billhassell.com]
    Envoyé : mercredi 7 juillet 2004 20:45
    À : 'HAUTECOEUR Bruno'
    Objet : RE: [HPADM] 32/64 bit architectures

    Actually, it is pretty simple. 64bits enables only one feature: extended
    addressing. There is no speed
    or performance advantage. Indeed, a highly computational-intensive program
    may grow slightly in size
    because many of the instructions and indexes are twice as large.
     
    Now a program that is only 32bits is extremely limited in what it can
    address. I say extremely because
    10 years ago, programs that were 500 megs in size were almost unheard of.
    Today, everyone is using
    massive arrays to speed up access, sorting, indexing, etc. So all of a
    sudden, the need to have data
    area inside a program that is larger than 1000 megs is very important.
     
    In HP-UX, the program address space is divided into 4 quadrants. In 32 bits,
    the quadrants are always
    limited to 1000 megs and cannot be changed. Thus, the maximum addressable
    space that a 32 program
    can have is 1000 megs (actually, 960megs). By changing a mapping option with
    chatr or with the compile
    and link programs, the first quadrant (text area) and the data quadrant can
    be combined forming about
    1750megs of addressable space. In 11.11 with patches, a 32bit program can
    actually extend the space
    to about 2500megs but with restrictions. These 32bit programs run in either
    a 32bit or 64bit version of
    HP-UX. But a 32bit version of HP-UX cannot 'see' any RAM above 3.75Gb.
     
    The world of Unix is 64bits. With HP-UX (not always true with other
    opsystems), 32bit programs run
    just fine on a 64bit processor with 64bit HP-UX.
     
    Bill

    -----Original Message-----
    From: hpux-admin-owner@DutchWorks.nl [mailto:hpux-admin-owner@DutchWorks.nl]
    On Behalf Of HAUTECOEUR Bruno
    Sent: Tuesday, July 06, 2004 4:43 AM
    To: hpadm
    Subject: [HPADM] 32/64 bit architectures

    Hi admins

    i am looking for a detailed document explaining the advantages /
    inconvenients between 32 and 64 bit architectures.

    Has somebody here such a doc or link to a doc or anything else in taht way ?

    TIA

    Rgds

    ________________
    Bruno HAUTECOEUR
    Architecte système Unix
    DSI / Architecture & Systèmes - Essilor International
    Tel: 33 (0)1 72 94 73 20 - Fax: 01 39 26 53 08
    mail: hautecob@essilor.fr 

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