Rich Felker
124b4ebc8a
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.
19 lines
436 B
C
19 lines
436 B
C
#include "pthread_impl.h"
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int pthread_mutex_lock(pthread_mutex_t *m)
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{
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int r;
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if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, 1))
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return 0;
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while ((r=pthread_mutex_trylock(m)) == EBUSY) {
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if (!(r=m->_m_lock) || (r&0x40000000)) continue;
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if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
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&& (r&0x1fffffff) == pthread_self()->tid)
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return EDEADLK;
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__wait(&m->_m_lock, &m->_m_waiters, r, 0);
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}
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return r;
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}
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