* Flow Table
* ==========
*
- * The flow table is a hash table of "flow entries". Each flow entry contains:
+ * The flow table is a collection of "flow entries". Each flow entry contains:
*
* - A "flow", that is, a summary of the headers in an Ethernet packet. The
- * flow is the hash key and thus must be unique within the flow table.
- * Flows are fine-grained entities that include L2, L3, and L4 headers. A
- * single TCP connection consists of two flows, one in each direction.
+ * flow must be unique within the flow table. Flows are fine-grained
+ * entities that include L2, L3, and L4 headers. A single TCP connection
+ * consists of two flows, one in each direction.
*
* In Open vSwitch userspace, "struct flow" is the typical way to describe
* a flow, but the datapath interface uses a different data format to
* "struct ovs_key_*" in include/linux/openvswitch.h for details.
* lib/odp-util.h defines several functions for working with these flows.
*
- * (In case you are familiar with OpenFlow, datapath flows are analogous
- * to OpenFlow flow matches. The most important difference is that
- * OpenFlow allows fields to be wildcarded and prioritized, whereas a
- * datapath's flow table is a hash table so every flow must be
- * exact-match, thus without priorities.)
+ * - A "mask" that, for each bit in the flow, specifies whether the datapath
+ * should consider the corresponding flow bit when deciding whether a
+ * given packet matches the flow entry. The original datapath design did
+ * not support matching: every flow entry was exact match. With the
+ * addition of a mask, the interface supports datapaths with a spectrum of
+ * wildcard matching capabilities, from those that only support exact
+ * matches to those that support bitwise wildcarding on the entire flow
+ * key, as well as datapaths with capabilities somewhere in between.
+ *
+ * Datapaths do not provide a way to query their wildcarding capabilities,
+ * nor is it expected that the client should attempt to probe for the
+ * details of their support. Instead, a client installs flows with masks
+ * that wildcard as many bits as acceptable. The datapath then actually
+ * wildcards as many of those bits as it can and changes the wildcard bits
+ * that it does not support into exact match bits. A datapath that can
+ * wildcard any bit, for example, would install the supplied mask, an
+ * exact-match only datapath would install an exact-match mask regardless
+ * of what mask the client supplied, and a datapath in the middle of the
+ * spectrum would selectively change some wildcard bits into exact match
+ * bits.
+ *
+ * Regardless of the requested or installed mask, the datapath retains the
+ * original flow supplied by the client. (It does not, for example, "zero
+ * out" the wildcarded bits.) This allows the client to unambiguously
+ * identify the flow entry in later flow table operations.
+ *
+ * The flow table does not have priorities; that is, all flow entries have
+ * equal priority. Detecting overlapping flow entries is expensive in
+ * general, so the datapath is not required to do it. It is primarily the
+ * client's responsibility not to install flow entries whose flow and mask
+ * combinations overlap.
*
* - A list of "actions" that tell the datapath what to do with packets
* within a flow. Some examples of actions are OVS_ACTION_ATTR_OUTPUT,
uint64_t n_missed; /* Number of flow table misses. */
uint64_t n_lost; /* Number of misses not sent to userspace. */
uint64_t n_flows; /* Number of flows present. */
+ uint64_t n_masks; /* Number of mega flow masks. */
+ uint64_t n_mask_hit; /* Number of mega flow masks visited for
+ flow table matches. */
};
int dpif_get_dp_stats(const struct dpif *, struct dpif_dp_stats *);
struct dpif_port *);
int dpif_port_get_name(struct dpif *, odp_port_t port_no,
char *name, size_t name_size);
-uint32_t dpif_get_max_ports(const struct dpif *);
uint32_t dpif_port_get_pid(const struct dpif *, odp_port_t port_no);
struct dpif_port_dump {
uint64_t n_packets;
uint64_t n_bytes;
long long int used;
- uint8_t tcp_flags;
+ uint16_t tcp_flags;
};
void dpif_flow_stats_extract(const struct flow *, const struct ofpbuf *packet,
git://git.onelab.eu / sliver-openvswitch.git / blobdiff