The addition of Geneve options to packet metadata significantly
expanded its size. It was reported that this can decrease performance
for DPDK ports by up to 25% since we need to initialize the whole
structure on each packet receive.
It is not really necessary to zero out the entire structure because
miniflow_extract() only copies the tunnel metadata when particular
fields indicate that it is valid. Therefore, as long as we zero out
these fields when the metadata is initialized and ensure that the
rest of the structure is correctly set in the presence of a tunnel,
we can avoid touching the tunnel fields on packet reception.
Reported-by: Ciara Loftus <ciara.loftus@intel.com>
Tested-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
Currently the userspace datapath only supports Geneve in a
basic mode - without options - since the rest of userspace
previously didn't support options either. This enables the
userspace datapath to send and receive options as well.
The receive path for extracting the tunnel options isn't entirely
optimal because it does a lookup on the options on a per-packet
basis, rather than per-flow like the kernel does. This is not
as straightforward to do in the userspace datapath since there
is no translation step between packet formats used in packet vs.
flow lookup. This can be optimized in the future and in the
meantime option support is still useful for testing and simulation.
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
The current support for Geneve in OVS is exactly equivalent to VXLAN:
it is possible to set and match on the VNI but not on any options
contained in the header. This patch enables the use of options.
The goal for Geneve support is not to add support for any particular option
but to allow end users or controllers to specify what they would like to
match. That is, the full range of Geneve's capabilities should be exposed
without modifying the code (the one exception being options that require
per-packet computation in the fast path).
The main issue with supporting Geneve options is how to integrate the
fields into the existing OpenFlow pipeline. All existing operations
are referred to by their NXM/OXM field name - matches, action generation,
arithmetic operations (i.e. tranfer to a register). However, the Geneve
option space is exactly the same as the OXM space, so a direct mapping
is not feasible. Instead, we create a pool of 64 NXMs that are then
dynamically mapped on Geneve option TLVs using OpenFlow. Once mapped,
these fields become first-class citizens in the OpenFlow pipeline.
An example of how to use Geneve options:
ovs-ofctl add-geneve-map br0 {class=0xffff,type=0,len=4}->tun_metadata0
ovs-ofctl add-flow br0 in_port=LOCAL,actions=set_field:0xffffffff->tun_metadata0,1
This will add a 4 bytes option (filled will all 1's) to all packets
coming from the LOCAL port and then send then out to port 1.
A limitation of this patch is that although the option table is specified
for a particular switch over OpenFlow, it is currently global to all
switches. This will be addressed in a future patch.
Based on work originally done by Madhu Challa. Ben Pfaff also significantly
improved the comments.
Signed-off-by: Madhu Challa <challa@noironetworks.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
In order to work with Geneve options, we need to maintain a mapping
table between an option (defined by <class, type, length>) and
an NXM field that can be operated on for the purposes of matches,
actions, etc. This mapping must be explicitly specified by the
user.
Conceptually, this table could be communicated using either OpenFlow
or OVSDB. Using OVSDB requires less code and definition of extensions
than OpenFlow but introduces the possibility that mapping table
updates and flow modifications are desynchronized from each other.
This is dangerous because the mapping table signifcantly impacts the
way that flows using Geneve options are installed and processed by
OVS. Therefore, the mapping table is maintained using OpenFlow commands
instead, which opens the possibility of using synchronization between
table changes and flow modifications through barriers, bundles, etc.
There are two primary groups of OpenFlow messages that are introduced
as Nicira extensions: modification commands (add, delete, clear mappings)
and table status request/reply to dump the current table along with switch
information.
Note that mappings should not be changed while they are in active use by
a flow. The result of doing so is undefined.
This only adds the OpenFlow infrastructure but doesn't actually
do anything with the information yet after the messages have been
decoded.
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
