datapath: Use __read_mostly annotations where appropriate.

Variables which are changed only infrequently should be annotated
with __read_mostly, which will group them together in a special
linker section.  This prevents them from sharing cache lines with
data on the hot path.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 522d4ec..bed4803 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -54,7 +54,6 @@
 
 #include "compat.h"
 
-
 int (*dp_ioctl_hook)(struct net_device *dev, struct ifreq *rq, int cmd);
 EXPORT_SYMBOL(dp_ioctl_hook);
 

diff --git a/datapath/flow.c b/datapath/flow.c
index 496f11c..d30fb73 100644 (file)
--- a/datapath/flow.c
+++ b/datapath/flow.c
@@ -32,7 +32,7 @@
 #include "compat.h"
 
 struct kmem_cache *flow_cache;
-static unsigned int hash_seed;
+static unsigned int hash_seed __read_mostly;
 
 static inline bool arphdr_ok(struct sk_buff *skb)
 {

diff --git a/datapath/tunnel.c b/datapath/tunnel.c
index f0ae98d..e666a91 100644 (file)
--- a/datapath/tunnel.c
+++ b/datapath/tunnel.c
@@ -68,7 +68,7 @@
 #define CACHE_DATA_ALIGN 16
 
 /* Protected by RCU. */
-static struct tbl *port_table;
+static struct tbl *port_table __read_mostly;
 
 static void cache_cleaner(struct work_struct *work);
 DECLARE_DELAYED_WORK(cache_cleaner_wq, cache_cleaner);
@@ -78,10 +78,10 @@ DECLARE_DELAYED_WORK(cache_cleaner_wq, cache_cleaner);
  * synchronization because we could have just as easily read the value before
  * the port change happened.
  */
-static unsigned int key_local_remote_ports;
-static unsigned int key_remote_ports;
-static unsigned int local_remote_ports;
-static unsigned int remote_ports;
+static unsigned int key_local_remote_ports __read_mostly;
+static unsigned int key_remote_ports __read_mostly;
+static unsigned int local_remote_ports __read_mostly;
+static unsigned int remote_ports __read_mostly;
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
 #define rt_dst(rt) (rt->dst)