From: Jarno Rajahalme <jrajahalme@nicira.com>
Date: Wed, 19 Mar 2014 15:51:52 +0000 (-0700)
Subject: lib/hmap: Remove the memory fence from hmap_is_empty().
X-Git-Tag: sliver-openvswitch-2.2.90-1~6^2~77
X-Git-Url: http://git.onelab.eu/?a=commitdiff_plain;h=543ede7e3eaac62c14a061296722839829b0cef8;p=sliver-openvswitch.git

lib/hmap: Remove the memory fence from hmap_is_empty().

The fence made classifier_lookup() slower.  Access to a size_t 'n' is
safe without synchonizing, and if racing with writers matters,
additional syncronization primitives are used anyway.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
---

diff --git a/lib/hmap.h b/lib/hmap.h
index 445e74f0b..9fb83d5ab 100644
--- a/lib/hmap.h
+++ b/lib/hmap.h
@@ -196,7 +196,6 @@ hmap_capacity(const struct hmap *hmap)
 static inline bool
 hmap_is_empty(const struct hmap *hmap)
 {
-    atomic_thread_fence(memory_order_acquire);
     return hmap->n == 0;
 }