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Date: Sat, 29 Aug 2015 10:50:44 +0200
From: Jens Gustedt <Jens.Gustedt@...ia.fr>
To: musl@...ts.openwall.com
Subject: [PATCH 1/2] let them spin
Remove a test in __wait that looked if other threads already attempted to
go to sleep in futex_wait.
This has no impact on the fast path. But other than one might think at a
first glance, this slows down if there is congestion.
Applying this patch shows no difference in behavior in a mono-core
setting, so it seems that this shortcut is just superfluous.
---
src/thread/__wait.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/thread/__wait.c b/src/thread/__wait.c
index dc33c1a..a93d41d 100644
--- a/src/thread/__wait.c
+++ b/src/thread/__wait.c
@@ -4,7 +4,7 @@ void __wait(volatile int *addr, volatile int *waiters, int val, int priv)
{
int spins=100;
if (priv) priv = FUTEX_PRIVATE;
- while (spins-- && (!waiters || !*waiters)) {
+ while (spins--) {
if (*addr==val) a_spin();
else return;
}
--
2.1.4
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