From: HAUTECOEUR Bruno (HAUTECOB@ESSILOR.fr)
Date: Thu Jul 08 2004 - 05:44:25 EDT
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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