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| author | Pádraig Brady <P@draigBrady.com> | 2010-12-18 05:27:46 +0000 |
|---|---|---|
| committer | Pádraig Brady <P@draigBrady.com> | 2010-12-19 00:33:45 +0000 |
| commit | 0e181024c00b746a930aab6a0cfd9162d7b67ae4 (patch) | |
| tree | 994336fac3c2c31ab31fa7b1b8700eb12c114243 /src | |
| parent | eea8e7530bf3c469dd7f4e598c993ff7fb4574e9 (diff) | |
| download | coreutils-0e181024c00b746a930aab6a0cfd9162d7b67ae4.tar.xz | |
sort: use at most 8 threads by default
* src/sort.c (main): If --parallel isn't specified,
restrict the number of threads to 8 by default.
If the --parallel option is specified, then
allow any number of threads to be set, independent
of the number of processors on the system.
* doc/coreutils.texi (sort invocation): Document the changes
to determining the number of threads to use.
Mention the memory overhead when using multiple threads.
* tests/misc/sort-spinlock-abuse: Allow single core
systems that support pthreads.
* tests/misc/sort-stale-thread-mem: Likewise.
* tests/misc/sort-unique-segv: Likewise.
* NEWS: Mention the change in behaviour.
Diffstat (limited to 'src')
| -rw-r--r-- | src/sort.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/src/sort.c b/src/sort.c index 54dd81528..6cc058896 100644 --- a/src/sort.c +++ b/src/sort.c @@ -116,6 +116,10 @@ struct rlimit { size_t rlim_cur; }; this number has any practical effect. */ enum { SUBTHREAD_LINES_HEURISTIC = 4 }; +/* The number of threads after which there are + diminishing performance gains. */ +enum { DEFAULT_MAX_THREADS = 8 }; + /* Exit statuses. */ enum { @@ -455,7 +459,7 @@ Other options:\n\ -t, --field-separator=SEP use SEP instead of non-blank to blank transition\n\ -T, --temporary-directory=DIR use DIR for temporaries, not $TMPDIR or %s;\n\ multiple options specify multiple directories\n\ - --parallel=N limit the number of sorts run concurrently to N\n\ + --parallel=N change the number sorts run concurrently to N\n\ -u, --unique with -c, check for strict ordering;\n\ without -c, output only the first of an equal run\n\ "), DEFAULT_TMPDIR); @@ -4595,14 +4599,15 @@ main (int argc, char **argv) } else { - unsigned long int np2 = num_processors (NPROC_CURRENT_OVERRIDABLE); - if (!nthreads || nthreads > np2) - nthreads = np2; + if (!nthreads) + { + nthreads = MIN (DEFAULT_MAX_THREADS, + num_processors (NPROC_CURRENT_OVERRIDABLE)); + } /* Avoid integer overflow later. */ size_t nthreads_max = SIZE_MAX / (2 * sizeof (struct merge_node)); - if (nthreads_max < nthreads) - nthreads = nthreads_max; + nthreads = MIN (nthreads, nthreads_max); sort (files, nfiles, outfile, nthreads); } |