From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Cc: Alexander Monakov <amonakov@ispras.ru>
Subject: [PATCH] Use CAS instead of atomic swap to implement spinlock
Date: Wed, 15 Apr 2015 01:44:53 +0300 [thread overview]
Message-ID: <1429051493-2821-1-git-send-email-amonakov@ispras.ru> (raw)
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
next reply other threads:[~2015-04-14 22:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-14 22:44 Alexander Monakov [this message]
2015-04-14 23:16 ` Rich Felker
2015-04-15 6:29 ` Concerns about dlclose() behaviour Brad Conroy
2015-04-15 7:17 ` Rich Felker
2015-04-19 0:24 ` [PATCH] Use CAS instead of atomic swap to implement spinlock Rich Felker
2015-04-19 5:50 ` Alexander Monakov
2015-04-19 6:01 ` Rich Felker
2015-04-19 12:46 ` Szabolcs Nagy
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