On Fri, Jul 01, 2016 at 12:43:02PM -0700, William Tu wrote: > This patch adds a 'snaplen' field in sample action (nx_action_sample2). > Currently, sample action is used by sFlow and IPFIX. For IPFIX, nothing > is changed. For sFlow configuration, the patch translates header=N to > a sample action with snaplen=N, then the snaplen=N translates to trunc(N) > in kernel datapath. Thus, only N bytes instead of full-packet size will > be copied from kernel to userspace, saving the copying overhead. > > Also, the patch parses OVS_PACKET_ATTR_LEN from nlattr to upcall related > structures so the sFlow receiver knows the original packet size before it > is truncated. > > Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/141704344 > Signed-off-by: William Tu <u9012...@gmail.com> > --- > v1->v2 > http://openvswitch.org/pipermail/dev/2016-June/072404.html > - Add snaplen to nx_action_sample2 > - Since truncate then userspace action is supported in userspace datapath, > ,commit aaca4fe0ce9e (ofp-actions: Add truncate action.), remove > datapath-specific implementation and testcase.
This changes the OpenFlow sample action but it doesn't document the new feature in ovs-ofctl(8). The new features should be mentioned in NEWS. In encode_SAMPLE(), NXAST_RAW_SAMPLE2 should also be selected if nas->snaplen != 0. In format_SAMPLE(), I would only output snaplen if it is nonzero (and not UINT16_MAX?). The datapath will reject a snaplen less than 14, but I don't see anything here that prevents userspace from trying such a snaplen. Thanks, Ben. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
