45 lines
1.6 KiB
Diff
45 lines
1.6 KiB
Diff
commit ae5fb9355918811679fa7ee01f1f41cea280b615
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Author: Sunil K Pandey <sunil.k.pandey@intel.com>
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Date: Tue Dec 9 08:57:44 2025 -0800
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nptl: Optimize trylock for high cache contention workloads (BZ #33704)
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Check lock availability before acquisition to reduce cache line
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bouncing. Significantly improves trylock throughput on multi-core
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systems under heavy contention.
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Tested on x86_64.
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Fixes BZ #33704.
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Co-authored-by: Alex M Wells <alex.m.wells@intel.com>
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Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
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(cherry picked from commit 63716823dbad9482e09972907ae98e9cb00f9b86)
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diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c
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index 720c103f3f1f92f7..6cf47403dd6a40fe 100644
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--- a/nptl/pthread_mutex_trylock.c
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+++ b/nptl/pthread_mutex_trylock.c
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@@ -48,7 +48,8 @@ ___pthread_mutex_trylock (pthread_mutex_t *mutex)
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return 0;
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}
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- if (lll_trylock (mutex->__data.__lock) == 0)
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+ if (atomic_load_relaxed (&(mutex->__data.__lock)) == 0
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+ && lll_trylock (mutex->__data.__lock) == 0)
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{
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/* Record the ownership. */
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mutex->__data.__owner = id;
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@@ -71,7 +72,10 @@ ___pthread_mutex_trylock (pthread_mutex_t *mutex)
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/*FALL THROUGH*/
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case PTHREAD_MUTEX_ADAPTIVE_NP:
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case PTHREAD_MUTEX_ERRORCHECK_NP:
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- if (lll_trylock (mutex->__data.__lock) != 0)
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+ /* Mutex type is already loaded, lock check overhead should
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+ be minimal. */
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+ if (atomic_load_relaxed (&(mutex->__data.__lock)) != 0
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+ || lll_trylock (mutex->__data.__lock) != 0)
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break;
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/* Record the ownership. */
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