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From: ron@topaz.rutgers.edu (Ron Natalie)
Newsgroups: comp.unix.wizards,comp.arch
Subject: Re: Large programs
Message-ID: <15746@topaz.rutgers.edu>
Date: Tue, 20-Oct-87 17:02:23 EDT
Article-I.D.: topaz.15746
Posted: Tue Oct 20 17:02:23 1987
Date-Received: Wed, 21-Oct-87 23:50:42 EDT
References: <1046@ius1.cs.cmu.edu> <1130@gilsys.UUCP> <2946@sol.ARPA> <918@cpocd2.UUCP>
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Organization: Rutgers Univ., New Brunswick, N.J.
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Keywords: UNIX LS HUMOR
Xref: mnetor comp.unix.wizards:5015 comp.arch:2681

Excuse me but pipes do file I/O on some systems (neglecting MiniUNIX
which doesn't have pipes and implements them with real files) real
UNIX pipes used disk I/O.  In non BSD implementations, an inode is
allocated and disk blocks are allocated.  Hopefully these stay in
the buffer cache rather than needing to be written to disk, but if
necessary they will get written out.  Back in the days before FSCK,
it was usually necessary to clri some of these pipe turds that were
left in a crash (they neither have directory entries nor a link count).

The System V R 2 V 3 on our 3B20 still does pipes this way.
Berkeley UNIX implements pipes as network sockets.  The data
is stored in MBUFS, I suppose as virtual memory these can get
paged out incurring disk I/O as well.

-Ron