From 7b8f497fe4ccac805ac4b20ff64946f0a5bbe4e3 Mon Sep 17 00:00:00 2001 From: Sunil K Pandey Date: Tue, 9 Dec 2025 08:57:44 -0800 Subject: [PATCH] nptl: Optimize trylock for high cache contention workloads (BZ #33704) Check lock availability before acquisition to reduce cache line bouncing. Significantly improves trylock throughput on multi-core systems under heavy contention. Tested on x86_64. Fixes BZ #33704. Co-authored-by: Alex M Wells Reviewed-by: Wilco Dijkstra (cherry picked from commit 63716823dbad9482e09972907ae98e9cb00f9b86) --- nptl/pthread_mutex_trylock.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c index 9b3a16954d..4ac283414d 100644 --- a/nptl/pthread_mutex_trylock.c +++ b/nptl/pthread_mutex_trylock.c @@ -48,7 +48,8 @@ ___pthread_mutex_trylock (pthread_mutex_t *mutex) return 0; } - if (lll_trylock (mutex->__data.__lock) == 0) + if (atomic_load_relaxed (&(mutex->__data.__lock)) == 0 + && lll_trylock (mutex->__data.__lock) == 0) { /* Record the ownership. */ mutex->__data.__owner = id; @@ -71,7 +72,10 @@ ___pthread_mutex_trylock (pthread_mutex_t *mutex) /*FALL THROUGH*/ case PTHREAD_MUTEX_ADAPTIVE_NP: case PTHREAD_MUTEX_ERRORCHECK_NP: - if (lll_trylock (mutex->__data.__lock) != 0) + /* Mutex type is already loaded, lock check overhead should + be minimal. */ + if (atomic_load_relaxed (&(mutex->__data.__lock)) != 0 + || lll_trylock (mutex->__data.__lock) != 0) break; /* Record the ownership. */