[PATCH v4 2/8] grep: skip pthreads overhead when using one thread
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Jun 1, 2017, 18:20 UTC
- Message-ID
- <20170601182056.31142-3-avarab@gmail.com>
- In-Reply-To
- <20170601182056.31142-1-avarab@gmail.com>
Skip the administrative overhead of using pthreads when only using one thread. Instead take the non-threaded path which would be taken under NO_PTHREADS.
The threading support was initially added in commit 5b594f457a ("Threaded grep", 2010-01-25) with a hardcoded compile-time number of 8 threads. Later the number of threads was made configurable in commit 89f09dd34e ("grep: add --threads=<num> option and grep.threads configuration", 2015-12-15).
That change did not add any special handling for --threads=1. Now we take a slightly faster path by skipping thread handling entirely when 1 thread is requested.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- builtin/grep.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/builtin/grep.c b/builtin/grep.c index 6e1744550c..a0a3922f92 100644 --- a/builtin/grep.c +++ b/builtin/grep.c @@ -1238,6 +1238,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix) num_threads = GREP_NUM_THREADS_DEFAULT; else if (num_threads < 0) die(_("invalid number of threads specified (%d)"), num_threads); + if (num_threads == 1) + num_threads = 0; #else if (num_threads) warning(_("no threads support, ignoring --threads"));
-- 2.13.0.303.g4ebf302169