psort(3) BSD Library Functions Manual psort(3)
NAME
psort, psort_b, psort_r -- parallel sort functions
SYNOPSIS
#include <stdlib.h>
void
psort(void *base, size_t nel, size_t width,
int (*compar)(const void *, const void *));
void
psort_b(void *base, size_t nel, size_t width,
int (^compar)(const void *, const void *));
void
psort_r(void *base, size_t nel, size_t width, void *thunk,
int (*compar)(void *, const void *, const void *));
DESCRIPTION
The psort(), psort_b(), and psort_r() functions are parallel sort rou-
tines that are drop-in compatible with the corresponding qsort() function
(see qsort(3) for a description of the arguments). On multiprocessor
machines, multiple threads may be created to simultaneously perform the
sort calculations, resulting in an overall faster sort result. Overhead
in managing the threads limits the maximum speed improvement to somewhat
less that the number of processors available. For example, on a 4-pro-
cessor machine, a typical sort on a large array might result in 3.2 times
faster sorting than a regular qsort().
RESTRICTIONS
Because of the multi-threaded nature of the sort, the comparison function
is expected to perform its own synchronization that might be required for
data physically outside the two objects passed to the comparison func-
tion. However, no synchronization is required for the two object them-
selves, unless some third party is also accessing those objects.
Additional memory is temporary allocated to deal with the parallel nature
of the computation.
Because of the overhead of maintaining multiple threads, the psort() fam-
ily of routines may choose to just call qsort(3) when there is no advan-
tage to parallelizing (for example, when the number of objects in the
array is too small, or only one processor is available).
Like qsort(3), the sort is not stable.
RETURN VALUES
The psort(), psort_b() and psort_r() functions return no value.
SEE ALSO
qsort(3)
SEE ALSO
sort(1), radixsort(3)
Hoare, C.A.R., "Quicksort", The Computer Journal, 5:1, pp. 10-15, 1962.
Williams, J.W.J, "Heapsort", Communications of the ACM, 7:1, pp. 347-348,
1964.
Knuth, D.E., "Sorting and Searching", The Art of Computer Programming,
Vol. 3, pp. 114-123, 145-149, 1968.
McIlroy, P.M., "Optimistic Sorting and Information Theoretic Complexity",
Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, January 1992.
Bentley, J.L. and McIlroy, M.D., "Engineering a Sort Function",
Software--Practice and Experience, Vol. 23(11), pp. 1249-1265,
November 1993.
STANDARDS
The qsort() function conforms to ISO/IEC 9899:1990 (``ISO C90'').
Mac OS X Nov 25, 2008 Mac OS X
Mac OS X 10.8 - Generated Wed Aug 29 19:46:54 CDT 2012