From: Piotr Dałek <piotr.dalek@ts.fujitsu.com>
Date: Thu, 19 Nov 2015 09:57:46 +0000 (+0100)
Subject: common/hobject.h: don't reverse bits in zero
X-Git-Tag: v10.0.2~167^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=9109f14ea10d6cd0dd0605a2e2b9ad8398cbf392;p=ceph.git

common/hobject.h: don't reverse bits in zero

Zero is passed in around 30% of all calls to _reverse_bits (and most of
them during daemon startup). Optimize this by not doing anything in
that special case and returning 0.

Signed-off-by: Piotr Dałek <piotr.dalek@ts.fujitsu.com>
---

diff --git a/src/common/hobject.h b/src/common/hobject.h
index 469875651555..601af40fa43f 100644
--- a/src/common/hobject.h
+++ b/src/common/hobject.h
@@ -176,6 +176,8 @@ public:
   }
 
   static uint32_t _reverse_bits(uint32_t v) {
+    if (v == 0)
+      return v;
     // reverse bits
     // swap odd and even bits
     v = ((v >> 1) & 0x55555555) | ((v & 0x55555555) << 1);