Re: [patch] morethan900MB-2.0.36

Leonard N. Zubkoff (
Fri, 4 Dec 1998 10:32:50 -0800

Date: Fri, 4 Dec 1998 16:50:53 +0100 (CET)
From: MOLNAR Ingo <>

we _definitely_ need support for more than 2G physical RAM. (eg. the
Torrent system demo on OracleWorld was run on a box with 2.5G RAM.) Also,
a 2G+2G split has performance disadvantages if the box in question has
less memory (eg. 1G RAM).

While allowing for more than 2GB physical memory makes sense in some cases, the
resulting limitation on the virtual address space size is going to be highly
problematic for many applications. For example, Oracle wants to use as much
memory as possible for its database block buffer cache which is mapped by all
Oracle processes as shared memory. Similarly, large scientific applications
probably need large individual data segments. It looks to me like the only
systems that can make use of more than 2GB physical memory will have a number
of smaller processes that don't share memory.

What's the performance disadvantage with a 2GB+2GB split?


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