Shared Memory in BSD4.3 is lacking?

[Bob Beck]

In article <12137 at brl-adm.ARPA> rbj at icst-cmr.arpa (Root Boy Jim) writes:
>
>Your friends at Sequent do the same thing. However, what they are
>really doing is marking certain pieces of the buffer cache resident
>and non-reclaimable, then mapping them into the processes space.

Not true.  mmap() works in Dynix by mapping portions of files into address
spaces on page boundaries.  The file acts as a paging source and store for
the data; the pages of the file are demand loaded directly into user
addressible memory, no buffer cache involved.  The buffer cache does remain
coherent, however, so read/write system calls see the latest data.

					Bob Beck
					Sequent Computer Systems
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					Beaverton, Oregon  97006
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