tunneling: Allow disabling tunnel header caching.

Tunnel header caching significantly improves performance by bypassing
much of the transmit path.  However, in some special cases or for
debugging it may be desirable to traverse the entire IP stack.  This
exposes that as an option (default is to enable header caching).

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

diff --git a/lib/netdev-tunnel.c b/lib/netdev-tunnel.c
index d0ecd98e204e7e603f6f392f570a282aebcf0292..fdc1d976a4fc493bd673dafcdc6c6bade0bc8751 100644 (file)
--- a/lib/netdev-tunnel.c
+++ b/lib/netdev-tunnel.c
@@ -66,6 +66,7 @@ parse_config(const char *name, const char *type, const struct shash *args,
     memset(config, 0, sizeof *config);
 
     config->flags |= TNL_F_PMTUD;
+    config->flags |= TNL_F_HDR_CACHE;
 
     SHASH_FOR_EACH (node, args) {
         if (!strcmp(node->name, "remote_ip")) {
@@ -121,6 +122,10 @@ parse_config(const char *name, const char *type, const struct shash *args,
             if (!strcmp(node->data, "false")) {
                 config->flags &= ~TNL_F_PMTUD;
             }
+        } else if (!strcmp(node->name, "header_cache")) {
+            if (!strcmp(node->data, "false")) {
+                config->flags &= ~TNL_F_HDR_CACHE;
+            }
         } else {
             VLOG_WARN("%s: unknown %s argument '%s'", name, type, node->name);
         }

diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index 6e255763d6063d664002faab57df27a50095852e..86fd3f9be8100ff12f9881d8c6bcf10bc7caafe8 100644 (file)
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -539,6 +539,17 @@
                 compliance with the IEEE 802.1D specification for bridges.
                 Default is enabled, set to <code>false</code> to disable.</dd>
             </dl>
+            <dl>
+              <dt><code>header_cache</code></dt>
+              <dd>Optional.  Enable caching of tunnel headers and the output
+               path.  This can lead to a significant performance increase
+               without changing behavior.  In general it should not be
+               necessary to adjust this setting.  However, the caching can
+               bypass certain components of the IP stack (such as IP tables)
+               and it may be useful to disable it if these features are
+               required or as a debugging measure.  Default is enabled, set to
+               <code>false</code> to disable.</dd>
+            </dl>
           </dd>
           <dt><code>capwap</code></dt>
           <dd>Ethernet tunneling over the UDP transport portion of CAPWAP
@@ -594,6 +605,17 @@
                 compliance with the IEEE 802.1D specification for bridges.
                 Default is enabled, set to <code>false</code> to disable.</dd>
             </dl>
+            <dl>
+              <dt><code>header_cache</code></dt>
+              <dd>Optional.  Enable caching of tunnel headers and the output
+               path.  This can lead to a significant performance increase
+               without changing behavior.  In general it should not be
+               necessary to adjust this setting.  However, the caching can
+               bypass certain components of the IP stack (such as IP tables)
+               and it may be useful to disable it if these features are
+               required or as a debugging measure.  Default is enabled, set to
+               <code>false</code> to disable.</dd>
+            </dl>
           </dd>
           <dt><code>patch</code></dt>
           <dd>