Linux has two patches to deal with that. One is the "highpte" patch which
allows page table entries in "high memory" (i.e. after 1Gb). The other is
"bigpages" which allows larger pages (i.e. 4mb instead of 4kb), thus fewer
page table entries. Both patches are for Red Hat AS 2.1. I imagine that
the proprietary UNIXes dealt with this a *long* time ago. Oracle and other
long-time UNIX ISVs are pretty much having to lead the Linux vendors by the
hand on such things...
- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
Sent: Tuesday, March 04, 2003 10:19 AM
>
> A late-breaking thought - but it's not my area
> of expertise, so others may laugh.
>
> If you have a very large SGA, don't you end
> up with a very large 'page table' at the O/S
> level to map virtual memory to real memory.
> And if you do, doesn't this affect the speed
> and cost of a context switch. If so, you may
> waste a lot of resources task-switching rather
> than working - especially if you system is
> designed to do a very large number of very
> small queries.
>
> Any comments from Unix hot-shots ?
>
> Regards
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
> Coming soon one-day tutorials:
> Cost Based Optimisation
> Trouble-shooting and Tuning
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> (see http://www.jlcomp.demon.co.uk/tutorial.html )
>
> ____UK_______March 19th
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> ____USA_(FL)_May 2nd
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>
> Next Seminar dates:
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>
>
> The Co-operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: 04 March 2003 13:38
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Jonathan Lewis
> INET: jonathan_at_jlcomp.demon.co.uk
>
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Received on Thu Mar 06 2003 - 00:33:59 CST
