CVS commit: src/usr.bin/sort

[David Laight <dsl%netbsd.org@localhost>]

Module Name:    src
Committed By:   dsl
Date:           Fri Oct  9 20:29:44 UTC 2009

Modified Files:
        src/usr.bin/sort: msort.c

Log Message:
When we need to merge more than 16 files, do them in a hierarchy.
Reduces the amount of data written to temporary files.
The 3-level stack has to do a simple reduce after 4352 input files, for
a normal file sort this is 35GB of data or about 500 million records.
This needs about 50 open fd's - which should be ok.
Clearly the merge sort could process more input files in one go - speeding
up the sort, but at some point the number of input files would exceed
whatever limit was applied.


To generate a diff of this commit:
cvs rdiff -u -r1.27 -r1.28 src/usr.bin/sort/msort.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.