openvswitch: Use skb_zerocopy() for upcall
Use of skb_zerocopy() can avoid the expensive call to memcpy()
when copying the packet data into the Netlink skb. Completes
checksum through skb_checksum_help() if not already done in
GSO segmentation.
Zerocopy is only performed if user space supported unaligned
Netlink messages. memory mapped netlink i/o is preferred over
zerocopy if it is set up.
Cost of upcall is significantly reduced from:
+ 7.48% vhost-8471 [k] memcpy
+ 5.57% ovs-vswitchd [k] memcpy
+ 2.81% vhost-8471 [k] csum_partial_copy_generic
to:
+ 5.72% ovs-vswitchd [k] memcpy
+ 3.32% vhost-5153 [k] memcpy
+ 0.68% vhost-5153 [k] skb_zerocopy
(megaflows disabled)
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>
1 file changed