When did paging get into System V
Daniel R. Levy
levy at ttrdc.UUCP
Sat May 14 09:32:22 AEST 1988
In article <7878 at brl-smoke.ARPA>, gwyn at brl-smoke.ARPA (Doug Gwyn ) writes:
# In article <382 at cloud9.UUCP> bob at cloud9.UUCP (Bob Toxen) writes:
# >About five years after Berkeley came out with it!
#
# So? Performance tests showed no significant performance advantage of
# demand paging over the then-current UNIX System V scheme of partial
# swapping. It was not until the additional advantages of an organized
# scheme like the UNIX System V region-oriented approach became apparent
# (e.g. shared libraries) that there was reason enough to implement it.
# Conversations I've had with kernel implementors indicate that, modulo
# a few glitches that can be readily corrected, the UNIX System V scheme
# (which resembles VMS's) is on the right track, and that Babaoglu's
# scheme embedded in 4BSD often has to be totally replaced. (Sun
# designed their original memory management hardware to look virtually
# the same as the VAX's, to avoid this. Not everyone has had that option.)
There is one very nice thing about SV paging (over swapping) that I have
noticed on 3B2 hardware: very large executables start up almost instantly
instead of taking many seconds to load. I don't know whether this
differential is true for Berkeley or not, or on VAXen, never having used
a non-paging Berkeley, or VAX UNIX system. Wizards?
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