Do inter-process pipes use secondary (disc) memory for buffering?

[Chris Torek]

> Recently, some controversy has arisen in my group regarding whether
> interprocess pipes use primary (main) or secondary (disc) memory for
> buffering.

The answer is "yes" and "yes".  System (III, V, Vr2, Vr2v2 [standard!])
and 4.1BSD (and 4.0 and 3.0 and 2.9 and 2.8BSD) implement pipes as disk
files.  4.2BSD implements them as sockets (which never go to disk).
However, in most cases the data in pipes never gets out of the block
file system buffer cache (main memory).

(Performance analysis?  What performance analysis?)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
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CSNet:	chris at umcp-cs		ARPA:	chris at maryland