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Date: Wed, 15 Apr 2015 01:44:53 +0300
From: Alexander Monakov <amonakov@...ras.ru>
To: musl@...ts.openwall.com
Cc: Alexander Monakov <amonakov@...ras.ru>
Subject: [PATCH] Use CAS instead of atomic swap to implement spinlock
This should allow spinning without constantly dirtying cache lines holding the
spinlock value. On architectures without native atomic swap, musl implement
a_swap by looping around a_cas.
---
If I'm not mistaken this was also suggested by nsz on IRC.
src/thread/pthread_spin_lock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/thread/pthread_spin_lock.c b/src/thread/pthread_spin_lock.c
index df575f0..dabcb31 100644
--- a/src/thread/pthread_spin_lock.c
+++ b/src/thread/pthread_spin_lock.c
@@ -2,6 +2,6 @@
int pthread_spin_lock(pthread_spinlock_t *s)
{
- while (a_swap(s, 1)) a_spin();
+ while (a_cas(s, 0, 1)) a_spin();
return 0;
}
--
2.1.3
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