diff options
| author | Rich Felker <dalias@aerifal.cx> | 2011-03-30 08:58:25 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2011-03-30 08:58:25 -0400 |
| commit | 124b4ebc8a293e616cc0a7eaba3587c9b7ff13ec (patch) | |
| tree | 80c2bdc3f961b6acb7344d5b8eaf725d219458d0 | |
| parent | 680630011d38eb9f96f92b2f080cc60f38f6df21 (diff) | |
| download | musl-124b4ebc8a293e616cc0a7eaba3587c9b7ff13ec.tar.gz | |
cheap special-case optimization for normal mutexes
cycle-level benchmark on atom cpu showed typical pthread_mutex_lock
call dropping from ~120 cycles to ~90 cycles with this change. benefit
may vary with compiler options and version, but this optimization is
very cheap to make and should always help some.
| -rw-r--r-- | src/thread/pthread_mutex_lock.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/thread/pthread_mutex_lock.c b/src/thread/pthread_mutex_lock.c index 477b3d80..87b19752 100644 --- a/src/thread/pthread_mutex_lock.c +++ b/src/thread/pthread_mutex_lock.c @@ -3,6 +3,10 @@ int pthread_mutex_lock(pthread_mutex_t *m) { int r; + + if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, 1)) + return 0; + while ((r=pthread_mutex_trylock(m)) == EBUSY) { if (!(r=m->_m_lock) || (r&0x40000000)) continue; if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK |