Complexity of reallocating storage (was users command crap)

[The Grey Wolf]

In article <5883:Feb102:05:4991 at kramden.acf.nyu.edu> brnstnd at kramden.acf.nyu.edu (Dan Bernstein) writes:
>
>To rephrase: You don't seem to know what good programming techniques
>are. Tradeoffs between speed, space, and human effort are important.
>Tradeoffs between ``multiple passes'' and ``single pass'' are entirely
>irrelevant when they aren't reflected in speed, space, or human effort.

As I'm sure someone will/has pointed out already (haven't seen it yet, but
then news has strange timing problems), multiple-pass contemplation of
a file is stable IFF the file is guaranteed not to be physically rearranged
between passes.  (Of course the same can be said of a single pass thru
a file, but the window is (usually) *much* smaller).  Examples where
multiple passes work is on (normally) stable files, such as running them
thru a compiler or running a disk thru fsck.  (Of course, even there,
anomalies happen...)

Side issue: -- has anyone managed a single-pass fsck?  That would
be tricky at best, possibly disastrous.  I thought for a moment that
instead of doing five passes, one could use five file descriptors to
handle each phase, seeing as the size of a disk partition is effectively
fixed (last I checked, anyway...).  But I guess the passes need to
happen in a particular order...

>
>---Dan


-- 
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