[ovs-dev,v5,3/3] revalidator: Rebalance offloaded flows based on the pps rate

Message ID 20180912142706.19969-4-sriharsha.basavapatna@broadcom.com
State Superseded
Headers show
Series
  • Support dynamic rebalancing of offloaded flows
Related show

Commit Message

Sriharsha Basavapatna via dev Sept. 12, 2018, 2:27 p.m.
This is the third patch in the patch-set to support dynamic rebalancing
of offloaded flows.

The dynamic rebalancing functionality is implemented in this patch. The
ukeys that are not scheduled for deletion are obtained and passed as input
to the rebalancing routine. The rebalancing is done in the context of
revalidation leader thread, after all other revalidator threads are
done with gathering rebalancing data for flows.

For each netdev that is in OOR state, a list of flows - both offloaded
and non-offloaded (pending) - is obtained using the ukeys. For each netdev
that is in OOR state, the flows are grouped and sorted into offloaded and
pending flows.  The offloaded flows are sorted in descending order of
pps-rate, while pending flows are sorted in ascending order of pps-rate.

The rebalancing is done in two phases. In the first phase, we try to
offload all pending flows and if that succeeds, the OOR state on the device
is cleared. If some (or none) of the pending flows could not be offloaded,
then we start replacing an offloaded flow that has a lower pps-rate than
a pending flow, until there are no more pending flows with a higher rate
than an offloaded flow. The flows that are replaced from the device are
added into kernel datapath.

A new OVS configuration parameter "offload-rebalance", is added to ovsdb.
The default value of this is "false". To enable this feature, set the
value of this parameter to "true", which provides packets-per-second
rate based policy to dynamically offload and un-offload flows.

Note: This option can be enabled only when 'hw-offload' policy is enabled.
It also requires 'tc-policy' to be set to 'skip_sw'; otherwise, flow
offload errors (specifically ENOSPC error this feature depends on) reported
by an offloaded device are supressed by TC-Flower kernel module.

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Co-authored-by: Venkat Duvvuru <venkatkumar.duvvuru@broadcom.com>
Signed-off-by: Venkat Duvvuru <venkatkumar.duvvuru@broadcom.com>
Reviewed-by: Sathya Perla <sathya.perla@broadcom.com>
---
 NEWS                          |   3 +
 lib/dpif-netdev.c             |   3 +-
 lib/dpif-netlink.c            |  20 +-
 lib/dpif-provider.h           |   8 +-
 lib/dpif.c                    |  30 ++-
 lib/dpif.h                    |  12 +-
 lib/netdev-provider.h         |   7 +-
 lib/netdev.c                  |  71 +++++-
 lib/netdev.h                  |   2 +
 ofproto/ofproto-dpif-upcall.c | 395 +++++++++++++++++++++++++++++++++-
 vswitchd/vswitch.xml          |  21 ++
 11 files changed, 541 insertions(+), 31 deletions(-)

Patch

diff --git a/NEWS b/NEWS
index 33b4d8a23..846b46fb5 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,9 @@  Post-v2.10.0
      as the default timeout for control utilities.
    - ovn:
      * ovn-ctl: allow passing user:group ids to the OVN daemons.
+   - ovs-vswitchd:
+     * New configuration option "offload-rebalance", that enables dynamic
+       rebalancing of offloaded flows.
 
 
 v2.10.0 - xx xxx xxxx
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 7c0300cc5..1c01d2278 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -3689,7 +3689,8 @@  dpif_netdev_execute(struct dpif *dpif, struct dpif_execute *execute)
 }
 
 static void
-dpif_netdev_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops)
+dpif_netdev_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops,
+                    enum dpif_offload_type offload_type OVS_UNUSED)
 {
     size_t i;
 
diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index 6ffe8af25..881dbc69c 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -2179,7 +2179,7 @@  parse_flow_put(struct dpif_netlink *dpif, struct dpif_flow_put *put)
         VLOG_DBG("added flow");
     } else if (err != EEXIST) {
         struct netdev *oor_netdev = NULL;
-        if (err == ENOSPC) {
+        if (err == ENOSPC && netdev_is_offload_rebalance_policy_enabled()) {
             oor_netdev = flow_get_tunnel_netdev(&match.flow.tunnel);
             if (!oor_netdev) {
                 oor_netdev = dev;
@@ -2274,7 +2274,8 @@  dpif_netlink_operate_chunks(struct dpif_netlink *dpif, struct dpif_op **ops,
 }
 
 static void
-dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
+dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops,
+                     enum dpif_offload_type offload_type)
 {
     struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
     struct dpif_op *new_ops[OPERATE_MAX_OPS];
@@ -2282,7 +2283,10 @@  dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
     int i = 0;
     int err = 0;
 
-    if (netdev_is_flow_api_enabled()) {
+    ovs_assert(offload_type != DPIF_OFFLOAD_ALWAYS ||
+               netdev_is_flow_api_enabled());
+
+    if (offload_type != DPIF_OFFLOAD_NEVER && netdev_is_flow_api_enabled()) {
         while (n_ops > 0) {
             count = 0;
 
@@ -2291,6 +2295,14 @@  dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
 
                 err = try_send_to_netdev(dpif, op);
                 if (err && err != EEXIST) {
+                    if (offload_type == DPIF_OFFLOAD_ALWAYS) {
+                        op->error = err;
+                        while (--n_ops) {
+                            op = ops[i++];
+                            op->error = err;
+                        }
+                        return;
+                    }
                     new_ops[count++] = op;
                 } else {
                     op->error = err;
@@ -2301,7 +2313,7 @@  dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
 
             dpif_netlink_operate_chunks(dpif, new_ops, count);
         }
-    } else {
+    } else if (offload_type != DPIF_OFFLOAD_ALWAYS) {
         dpif_netlink_operate_chunks(dpif, ops, n_ops);
     }
 }
diff --git a/lib/dpif-provider.h b/lib/dpif-provider.h
index 7a71f5c0a..a30de740f 100644
--- a/lib/dpif-provider.h
+++ b/lib/dpif-provider.h
@@ -296,12 +296,14 @@  struct dpif_class {
 
     int (*flow_dump_next)(struct dpif_flow_dump_thread *thread,
                           struct dpif_flow *flows, int max_flows);
-
     /* Executes each of the 'n_ops' operations in 'ops' on 'dpif', in the order
      * in which they are specified, placing each operation's results in the
      * "output" members documented in comments and the 'error' member of each
-     * dpif_op. */
-    void (*operate)(struct dpif *dpif, struct dpif_op **ops, size_t n_ops);
+     * dpif_op. The offload_type argument tells the provider if 'ops' should
+     * be submitted to to a netdev (only offload) or to the kernel datapath
+     * (never offload) or to both (offload if possible; software fallback). */
+    void (*operate)(struct dpif *dpif, struct dpif_op **ops, size_t n_ops,
+                    enum dpif_offload_type offload_type);
 
     /* Enables or disables receiving packets with dpif_recv() for 'dpif'.
      * Turning packet receive off and then back on is allowed to change Netlink
diff --git a/lib/dpif.c b/lib/dpif.c
index d799f972c..65880b86a 100644
--- a/lib/dpif.c
+++ b/lib/dpif.c
@@ -49,6 +49,7 @@ 
 #include "valgrind.h"
 #include "openvswitch/ofp-errors.h"
 #include "openvswitch/vlog.h"
+#include "lib/netdev-provider.h"
 
 VLOG_DEFINE_THIS_MODULE(dpif);
 
@@ -1015,7 +1016,7 @@  dpif_flow_get(struct dpif *dpif,
     op.flow_get.flow->key_len = key_len;
 
     opp = &op;
-    dpif_operate(dpif, &opp, 1);
+    dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
 
     return op.error;
 }
@@ -1045,7 +1046,7 @@  dpif_flow_put(struct dpif *dpif, enum dpif_flow_put_flags flags,
     op.flow_put.stats = stats;
 
     opp = &op;
-    dpif_operate(dpif, &opp, 1);
+    dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
 
     return op.error;
 }
@@ -1068,7 +1069,7 @@  dpif_flow_del(struct dpif *dpif,
     op.flow_del.terse = false;
 
     opp = &op;
-    dpif_operate(dpif, &opp, 1);
+    dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
 
     return op.error;
 }
@@ -1325,7 +1326,7 @@  dpif_execute(struct dpif *dpif, struct dpif_execute *execute)
         op.execute = *execute;
 
         opp = &op;
-        dpif_operate(dpif, &opp, 1);
+        dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
 
         return op.error;
     } else {
@@ -1336,10 +1337,21 @@  dpif_execute(struct dpif *dpif, struct dpif_execute *execute)
 /* Executes each of the 'n_ops' operations in 'ops' on 'dpif', in the order in
  * which they are specified.  Places each operation's results in the "output"
  * members documented in comments, and 0 in the 'error' member on success or a
- * positive errno on failure. */
+ * positive errno on failure.
+ */
 void
-dpif_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops)
-{
+dpif_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops,
+             enum dpif_offload_type offload_type)
+{
+    if (offload_type == DPIF_OFFLOAD_ALWAYS && !netdev_is_flow_api_enabled()) {
+        size_t i;
+        for (i = 0; i < n_ops; i++) {
+            struct dpif_op *op = ops[i];
+            op->error = EINVAL;
+        }
+        return;
+    }
+
     while (n_ops > 0) {
         size_t chunk;
 
@@ -1360,7 +1372,7 @@  dpif_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops)
              * handle itself, without help. */
             size_t i;
 
-            dpif->dpif_class->operate(dpif, ops, chunk);
+            dpif->dpif_class->operate(dpif, ops, chunk, offload_type);
 
             for (i = 0; i < chunk; i++) {
                 struct dpif_op *op = ops[i];
@@ -1657,7 +1669,7 @@  dpif_queue_to_priority(const struct dpif *dpif, uint32_t queue_id,
     log_operation(dpif, "queue_to_priority", error);
     return error;
 }
-
+
 void
 dpif_init(struct dpif *dpif, const struct dpif_class *dpif_class,
           const char *name,
diff --git a/lib/dpif.h b/lib/dpif.h
index bbdc3eb6c..0675ab19f 100644
--- a/lib/dpif.h
+++ b/lib/dpif.h
@@ -614,6 +614,13 @@  enum dpif_op_type {
     DPIF_OP_FLOW_GET,
 };
 
+/* offload_type argument types to (*operate) interface */
+enum dpif_offload_type {
+    DPIF_OFFLOAD_AUTO,         /* Offload if possible, fallback to software. */
+    DPIF_OFFLOAD_NEVER,        /* Never offload to hardware. */
+    DPIF_OFFLOAD_ALWAYS,       /* Always offload to hardware. */
+};
+
 /* Add or modify a flow.
  *
  * The flow is specified by the Netlink attributes with types OVS_KEY_ATTR_* in
@@ -768,8 +775,9 @@  struct dpif_op {
     };
 };
 
-void dpif_operate(struct dpif *, struct dpif_op **ops, size_t n_ops);
-
+void dpif_operate(struct dpif *, struct dpif_op **ops, size_t n_ops,
+                  enum dpif_offload_type);
+
 /* Upcalls. */
 
 enum dpif_upcall_type {
diff --git a/lib/netdev-provider.h b/lib/netdev-provider.h
index e320dad61..fb0c27e6e 100644
--- a/lib/netdev-provider.h
+++ b/lib/netdev-provider.h
@@ -38,10 +38,14 @@  struct netdev_tnl_build_header_params;
 /* Offload-capable (HW) netdev information */
 struct netdev_hw_info {
     bool oor;		/* Out of Offload Resources ? */
+    int offload_count;  /* Pending (non-offloaded) flow count */
+    int pending_count;  /* Offloaded flow count */
 };
 
 enum hw_info_type {
-    HW_INFO_TYPE_OOR = 1	/* OOR state */
+    HW_INFO_TYPE_OOR = 1,		/* OOR state */
+    HW_INFO_TYPE_PEND_COUNT = 2,	/* Pending(non-offloaded) flow count */
+    HW_INFO_TYPE_OFFL_COUNT = 3		/* Offloaded flow count */
 };
 
 /* A network device (e.g. an Ethernet device).
@@ -89,7 +93,6 @@  struct netdev {
     int n_rxq;
     struct shash_node *node;            /* Pointer to element in global map. */
     struct ovs_list saved_flags_list; /* Contains "struct netdev_saved_flags". */
-
     struct netdev_hw_info hw_info;	/* offload-capable netdev info */
 };
 
diff --git a/lib/netdev.c b/lib/netdev.c
index 5ec4c935f..5a61bbd2e 100644
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -2260,11 +2260,23 @@  netdev_get_block_id(struct netdev *netdev)
 int
 netdev_get_hw_info(struct netdev *netdev, int type)
 {
-    if (type == HW_INFO_TYPE_OOR) {
-        return netdev->hw_info.oor;
+    int val = -1;
+
+    switch (type) {
+    case HW_INFO_TYPE_OOR:
+        val = netdev->hw_info.oor;
+        break;
+    case HW_INFO_TYPE_PEND_COUNT:
+        val = netdev->hw_info.pending_count;
+        break;
+    case HW_INFO_TYPE_OFFL_COUNT:
+        val = netdev->hw_info.offload_count;
+        break;
+    default:
+        break;
     }
 
-    return -1;
+    return val;
 }
 
 /*
@@ -2273,9 +2285,47 @@  netdev_get_hw_info(struct netdev *netdev, int type)
 void
 netdev_set_hw_info(struct netdev *netdev, int type, int val)
 {
-    if (type == HW_INFO_TYPE_OOR) {
+    switch (type) {
+    case HW_INFO_TYPE_OOR:
+        if (val == 0) {
+            VLOG_DBG("Offload rebalance: netdev: %s is not OOR", netdev->name);
+        }
         netdev->hw_info.oor = val;
+        break;
+    case HW_INFO_TYPE_PEND_COUNT:
+        netdev->hw_info.pending_count = val;
+        break;
+    case HW_INFO_TYPE_OFFL_COUNT:
+        netdev->hw_info.offload_count = val;
+        break;
+    default:
+        break;
+    }
+}
+
+/*
+ * Find if any netdev is in OOR state. Return true if there's at least
+ * one netdev that's in OOR state; otherwise return false.
+ */
+bool
+netdev_any_oor(void)
+    OVS_EXCLUDED(netdev_mutex)
+{
+    struct shash_node *node;
+    bool oor = false;
+
+    ovs_mutex_lock(&netdev_mutex);
+    SHASH_FOR_EACH (node, &netdev_shash) {
+        struct netdev *dev = node->data;
+
+        if (dev->hw_info.oor) {
+            oor = true;
+            break;
+        }
     }
+    ovs_mutex_unlock(&netdev_mutex);
+
+    return oor;
 }
 
 bool
@@ -2515,6 +2565,15 @@  netdev_free_custom_stats_counters(struct netdev_custom_stats *custom_stats)
 }
 
 #ifdef __linux__
+
+static bool netdev_offload_rebalance_policy = false;
+
+bool
+netdev_is_offload_rebalance_policy_enabled(void)
+{
+    return netdev_offload_rebalance_policy;
+}
+
 static void
 netdev_ports_flow_init(void)
 {
@@ -2541,6 +2600,10 @@  netdev_set_flow_api_enabled(const struct smap *ovs_other_config)
             tc_set_policy(smap_get_def(ovs_other_config, "tc-policy",
                                        TC_POLICY_DEFAULT));
 
+            if (smap_get_bool(ovs_other_config, "offload-rebalance", false)) {
+                netdev_offload_rebalance_policy = true;
+            }
+
             netdev_ports_flow_init();
 
             ovsthread_once_done(&once);
diff --git a/lib/netdev.h b/lib/netdev.h
index dea727fcf..373be7cc0 100644
--- a/lib/netdev.h
+++ b/lib/netdev.h
@@ -229,8 +229,10 @@  int netdev_init_flow_api(struct netdev *);
 uint32_t netdev_get_block_id(struct netdev *);
 int netdev_get_hw_info(struct netdev *, int);
 void netdev_set_hw_info(struct netdev *, int, int);
+bool netdev_any_oor(void);
 bool netdev_is_flow_api_enabled(void);
 void netdev_set_flow_api_enabled(const struct smap *ovs_other_config);
+bool netdev_is_offload_rebalance_policy_enabled(void);
 
 struct dpif_port;
 int netdev_ports_insert(struct netdev *, const struct dpif_class *,
diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
index ef64b9c48..b6dc9de82 100644
--- a/ofproto/ofproto-dpif-upcall.c
+++ b/ofproto/ofproto-dpif-upcall.c
@@ -22,6 +22,7 @@ 
 #include "connmgr.h"
 #include "coverage.h"
 #include "cmap.h"
+#include "lib/dpif-provider.h"
 #include "dpif.h"
 #include "openvswitch/dynamic-string.h"
 #include "fail-open.h"
@@ -42,7 +43,6 @@ 
 #include "tunnel.h"
 #include "unixctl.h"
 #include "openvswitch/vlog.h"
-#include "lib/dpif-provider.h"
 #include "lib/netdev-provider.h"
 
 #define MAX_QUEUE_LENGTH 512
@@ -182,6 +182,8 @@  struct udpif {
     uint64_t conn_seq;                 /* Corresponds to 'dump_seq' when
                                           conns[n_conns-1] was stored. */
     size_t n_conns;                    /* Number of connections waiting. */
+
+    long long int offload_rebalance_time;  /* Time of last offload rebalance */
 };
 
 enum upcall_type {
@@ -398,6 +400,12 @@  static int upcall_receive(struct upcall *, const struct dpif_backer *,
                           const ovs_u128 *ufid, const unsigned pmd_id);
 static void upcall_uninit(struct upcall *);
 
+static void udpif_flow_rebalance(struct udpif *udpif);
+static int udpif_flow_program(struct udpif *udpif, struct udpif_key *ukey,
+                              enum dpif_offload_type offload_type);
+static int udpif_flow_unprogram(struct udpif *udpif, struct udpif_key *ukey,
+                                enum dpif_offload_type offload_type);
+
 static upcall_callback upcall_cb;
 static dp_purge_callback dp_purge_cb;
 
@@ -569,6 +577,7 @@  udpif_start_threads(struct udpif *udpif, size_t n_handlers_,
         ovs_barrier_init(&udpif->pause_barrier, udpif->n_revalidators + 1);
         udpif->reval_exit = false;
         udpif->pause = false;
+        udpif->offload_rebalance_time = time_msec();
         udpif->revalidators = xzalloc(udpif->n_revalidators
                                       * sizeof *udpif->revalidators);
         for (size_t i = 0; i < udpif->n_revalidators; i++) {
@@ -861,6 +870,26 @@  free_dupcall:
     return n_upcalls;
 }
 
+static void
+udpif_run_flow_rebalance(struct udpif *udpif)
+{
+    long long int now = 0;
+
+    /* Don't rebalance if OFFL_REBAL_INTVL_MSEC have not elapsed */
+    now = time_msec();
+    if (now < udpif->offload_rebalance_time + OFFL_REBAL_INTVL_MSEC) {
+        return;
+    }
+
+    if (!netdev_any_oor()) {
+        return;
+    }
+
+    VLOG_DBG("Offload rebalance: Found OOR netdevs");
+    udpif->offload_rebalance_time = now;
+    udpif_flow_rebalance(udpif);
+}
+
 static void *
 udpif_revalidator(void *arg)
 {
@@ -935,6 +964,9 @@  udpif_revalidator(void *arg)
 
             dpif_flow_dump_destroy(udpif->dump);
             seq_change(udpif->dump_seq);
+            if (netdev_is_offload_rebalance_policy_enabled()) {
+                udpif_run_flow_rebalance(udpif);
+            }
 
             duration = MAX(time_msec() - start_time, 1);
             udpif->dump_duration = duration;
@@ -979,7 +1011,7 @@  udpif_revalidator(void *arg)
 
     return NULL;
 }
-
+
 static enum upcall_type
 classify_upcall(enum dpif_upcall_type type, const struct nlattr *userdata,
                 struct user_action_cookie *cookie)
@@ -1581,7 +1613,7 @@  handle_upcalls(struct udpif *udpif, struct upcall *upcalls,
     for (i = 0; i < n_ops; i++) {
         opsp[n_opsp++] = &ops[i].dop;
     }
-    dpif_operate(udpif->dpif, opsp, n_opsp);
+    dpif_operate(udpif->dpif, opsp, n_opsp, DPIF_OFFLOAD_AUTO);
     for (i = 0; i < n_ops; i++) {
         struct udpif_key *ukey = ops[i].ukey;
 
@@ -1673,7 +1705,7 @@  ukey_create__(const struct nlattr *key, size_t key_len,
     ukey->state = UKEY_CREATED;
     ukey->state_thread = ovsthread_id_self();
     ukey->state_where = OVS_SOURCE_LOCATOR;
-    ukey->created = time_msec();
+    ukey->created = ukey->flow_time = time_msec();
     memset(&ukey->stats, 0, sizeof ukey->stats);
     ukey->stats.used = used;
     ukey->xcache = NULL;
@@ -2332,7 +2364,7 @@  push_dp_ops(struct udpif *udpif, struct ukey_op *ops, size_t n_ops)
     for (i = 0; i < n_ops; i++) {
         opsp[i] = &ops[i].dop;
     }
-    dpif_operate(udpif->dpif, opsp, n_ops);
+    dpif_operate(udpif->dpif, opsp, n_ops, DPIF_OFFLOAD_AUTO);
 
     for (i = 0; i < n_ops; i++) {
         struct ukey_op *op = &ops[i];
@@ -2544,6 +2576,16 @@  udpif_flow_time_delta(struct udpif *udpif, struct udpif_key *ukey)
     return (udpif->dpif->current_ms - ukey->flow_time) / 1000;
 }
 
+/*
+ * Save backlog packet count while switching modes
+ * between offloaded and kernel datapaths.
+ */
+static void
+udpif_set_ukey_backlog_packets(struct udpif_key *ukey)
+{
+    ukey->flow_backlog_packets = ukey->flow_packets;
+}
+
 /* Gather pps-rate for the given dpif_flow and save it in its ukey */
 static void
 udpif_update_flow_pps(struct udpif *udpif, struct udpif_key *ukey,
@@ -2618,6 +2660,7 @@  revalidate(struct revalidator *revalidator)
         kill_them_all = n_dp_flows > flow_limit * 2;
         max_idle = n_dp_flows > flow_limit ? 100 : ofproto_max_idle;
 
+        udpif->dpif->current_ms = time_msec();
         for (f = flows; f < &flows[n_dumped]; f++) {
             long long int used = f->stats.used;
             struct recirc_refs recircs = RECIRC_REFS_EMPTY_INITIALIZER;
@@ -2675,7 +2718,8 @@  revalidate(struct revalidator *revalidator)
             }
             ukey->dump_seq = dump_seq;
 
-            if (result != UKEY_DELETE) {
+            if (netdev_is_offload_rebalance_policy_enabled() &&
+                result != UKEY_DELETE) {
                 udpif_update_flow_pps(udpif, ukey, f);
             }
 
@@ -2993,3 +3037,342 @@  upcall_unixctl_purge(struct unixctl_conn *conn, int argc OVS_UNUSED,
     }
     unixctl_command_reply(conn, "");
 }
+
+/* Flows are sorted in the following order:
+ * netdev, flow state (offloaded/kernel path), flow_pps_rate.
+ */
+static int
+flow_compare_rebalance(const void *elem1, const void *elem2)
+{
+    const struct udpif_key *f1 = *(struct udpif_key **)elem1;
+    const struct udpif_key *f2 = *(struct udpif_key **)elem2;
+    int64_t diff;
+
+    if (f1->in_netdev < f2->in_netdev) {
+        return -1;
+    } else if (f1->in_netdev > f2->in_netdev) {
+        return 1;
+    }
+
+    if (f1->offloaded != f2->offloaded) {
+        return f2->offloaded - f1->offloaded;
+    }
+
+    diff = (f1->offloaded == true) ?
+        f1->flow_pps_rate - f2->flow_pps_rate :
+        f2->flow_pps_rate - f1->flow_pps_rate;
+
+    return (diff < 0) ? -1 : 1;
+}
+
+/* Insert flows from pending array during rebalancing */
+static int
+rebalance_insert_pending(struct udpif *udpif, struct udpif_key **pending_flows,
+                         int pending_count, int insert_count,
+                         uint64_t rate_threshold)
+{
+    int i, err = 0;
+    struct udpif_key *flow;
+    int count = 0;
+
+    for (i = 0; i < pending_count; i++) {
+        flow = pending_flows[i];
+
+        /* Stop offloading pending flows if the insert count is
+         * reached and the flow rate is less than the threshold
+         */
+        if (count >= insert_count && flow->flow_pps_rate < rate_threshold) {
+                break;
+        }
+
+        /* Offload the flow to netdev */
+        err = udpif_flow_program(udpif, flow, DPIF_OFFLOAD_ALWAYS);
+
+        if (err == ENOSPC) {
+            /* Stop if we are out of resources */
+            break;
+        }
+
+        if (err) {
+            continue;
+        }
+
+        /* Offload succeeded; delete it from the kernel datapath */
+        udpif_flow_unprogram(udpif, flow, DPIF_OFFLOAD_NEVER);
+
+        /* Change the state of the flow, adjust dpif counters */
+        flow->offloaded = true;
+
+        udpif_set_ukey_backlog_packets(flow);
+        count++;
+    }
+
+    return count;
+}
+
+/* Remove flows from offloaded array during rebalancing */
+static void
+rebalance_remove_offloaded(struct udpif *udpif,
+                           struct udpif_key **offloaded_flows,
+                           int offload_count)
+{
+    int i;
+    struct udpif_key *flow;
+
+    for (i = 0; i < offload_count; i++) {
+        flow = offloaded_flows[i];
+
+        /* Remove offloaded flow from netdev */
+        udpif_flow_unprogram(udpif, flow, DPIF_OFFLOAD_ALWAYS);
+
+        /* Install the flow into kernel path */
+        udpif_flow_program(udpif, flow, DPIF_OFFLOAD_NEVER);
+        flow->offloaded = false;
+
+        udpif_set_ukey_backlog_packets(flow);
+    }
+}
+
+/*
+ * Rebalance offloaded flows on a netdev that's in OOR state.
+ *
+ * The rebalancing is done in two phases. In the first phase, we check if
+ * the pending flows can be offloaded (if some resources became available
+ * in the meantime) by trying to offload each pending flow. If all pending
+ * flows get successfully offloaded, the OOR state is cleared on the netdev
+ * and there's nothing to rebalance.
+ *
+ * If some of the pending flows could not be offloaded, i.e, we still see
+ * the OOR error, then we move to the second phase of rebalancing. In this
+ * phase, the rebalancer compares pps-rate of an offloaded flow with the
+ * least pps-rate with that of a pending flow with the highest pps-rate from
+ * their respective sorted arrays. If pps-rate of the offloaded flow is less
+ * than the pps-rate of the pending flow, then it deletes the offloaded flow
+ * from the HW/netdev and adds it to kernel datapath and then offloads pending
+ * to HW/netdev. This process is repeated for every pair of offloaded and
+ * pending flows in the ordered list. The process stops when we encounter an
+ * offloaded flow that has a higher pps-rate than the corresponding pending
+ * flow. The entire rebalancing process is repeated in the next iteration.
+ */
+static bool
+rebalance_device(struct udpif *udpif, struct udpif_key **offloaded_flows,
+                 int offload_count, struct udpif_key **pending_flows,
+                 int pending_count)
+{
+
+    /* Phase 1 */
+    int num_inserted = rebalance_insert_pending(udpif, pending_flows,
+                                                pending_count, pending_count,
+                                                0);
+    if (num_inserted) {
+        VLOG_DBG("Offload rebalance: Phase1: inserted %d pending flows",
+                  num_inserted);
+    }
+
+    /* Adjust pending array */
+    pending_flows = &pending_flows[num_inserted];
+    pending_count -= num_inserted;
+
+    if (!pending_count) {
+        /*
+         * Successfully offloaded all pending flows. The device
+         * is no longer in OOR state; done rebalancing this device.
+         */
+        return false;
+    }
+
+    /*
+     * Phase 2; determine how many offloaded flows to churn.
+     */
+#define	OFFL_REBAL_MAX_CHURN    1024
+    int churn_count = 0;
+    while (churn_count < OFFL_REBAL_MAX_CHURN && churn_count < offload_count
+           && churn_count < pending_count) {
+        if (pending_flows[churn_count]->flow_pps_rate <=
+            offloaded_flows[churn_count]->flow_pps_rate)
+                break;
+        churn_count++;
+    }
+
+    if (churn_count) {
+        VLOG_DBG("Offload rebalance: Phase2: removed %d offloaded flows",
+                  churn_count);
+    }
+
+    /* Bail early if nothing to churn */
+    if (!churn_count) {
+        return true;
+    }
+
+    /* Remove offloaded flows */
+    rebalance_remove_offloaded(udpif, offloaded_flows, churn_count);
+
+    /* Adjust offloaded array */
+    offloaded_flows = &offloaded_flows[churn_count];
+    offload_count -= churn_count;
+
+    /* Replace offloaded flows with pending flows */
+    num_inserted = rebalance_insert_pending(udpif, pending_flows,
+                                            pending_count, churn_count,
+                                            offload_count ?
+                                            offloaded_flows[0]->flow_pps_rate :
+                                            0);
+    if (num_inserted) {
+        VLOG_DBG("Offload rebalance: Phase2: inserted %d pending flows",
+                  num_inserted);
+    }
+
+    return true;
+}
+
+static struct udpif_key **
+udpif_add_oor_flows(struct udpif_key **sort_flows, size_t *total_flow_count,
+                    size_t *alloc_flow_count, struct udpif_key *ukey)
+{
+    if (*total_flow_count >= *alloc_flow_count) {
+        sort_flows = x2nrealloc(sort_flows, alloc_flow_count, sizeof ukey);
+    }
+    sort_flows[(*total_flow_count)++] = ukey;
+    return sort_flows;
+}
+
+/*
+ * Build sort_flows[] initially with flows that
+ * reference an 'OOR' netdev as their input port.
+ */
+static struct udpif_key **
+udpif_build_oor_flows(struct udpif_key **sort_flows, size_t *total_flow_count,
+                      size_t *alloc_flow_count, struct udpif_key *ukey,
+                      int *oor_netdev_count)
+{
+    struct netdev *netdev;
+    int count;
+
+    /* Both input and output netdevs must be available for the flow */
+    if (!ukey->in_netdev || !ukey->out_netdev) {
+        ukey_netdev_unref(ukey);
+        return sort_flows;
+    }
+
+    /* Get input netdev for the flow */
+    netdev = ukey->in_netdev;
+
+    /* Is the in-netdev for this flow in OOR state ? */
+    if (!netdev_get_hw_info(netdev, HW_INFO_TYPE_OOR)) {
+        ukey_netdev_unref(ukey);
+        return sort_flows;
+    }
+
+    /* Add the flow to sort_flows[] */
+    sort_flows = udpif_add_oor_flows(sort_flows, total_flow_count,
+                                      alloc_flow_count, ukey);
+    if (ukey->offloaded) {
+        count = netdev_get_hw_info(netdev, HW_INFO_TYPE_OFFL_COUNT);
+        ovs_assert(count >= 0);
+        if (count++ == 0) {
+            (*oor_netdev_count)++;
+        }
+        netdev_set_hw_info(netdev, HW_INFO_TYPE_OFFL_COUNT, count);
+    } else {
+        count = netdev_get_hw_info(netdev, HW_INFO_TYPE_PEND_COUNT);
+        ovs_assert(count >= 0);
+        netdev_set_hw_info(netdev, HW_INFO_TYPE_PEND_COUNT, ++count);
+    }
+
+    return sort_flows;
+}
+
+/*
+ * Rebalance offloaded flows on HW netdevs that are in OOR state.
+ */
+static void
+udpif_flow_rebalance(struct udpif *udpif)
+{
+    struct udpif_key **sort_flows = NULL;
+    size_t alloc_flow_count = 0;
+    size_t total_flow_count = 0;
+    int oor_netdev_count = 0;
+    int offload_index = 0;
+    int pending_index;
+
+    /* Collect flows (offloaded and pending) that reference OOR netdevs */
+    for (size_t i = 0; i < N_UMAPS; i++) {
+        struct udpif_key *ukey;
+        struct umap *umap = &udpif->ukeys[i];
+
+        CMAP_FOR_EACH (ukey, cmap_node, &umap->cmap) {
+            ukey_to_flow_netdevs(udpif, ukey);
+            sort_flows = udpif_build_oor_flows(sort_flows, &total_flow_count,
+                                               &alloc_flow_count, ukey,
+                                               &oor_netdev_count);
+        }
+    }
+
+    /* Sort flows by OOR netdevs, state (offloaded/pending) and pps-rate  */
+    qsort(sort_flows, total_flow_count, sizeof(struct udpif_key *),
+          flow_compare_rebalance);
+
+    /*
+     * We now have flows referencing OOR netdevs, that are sorted. We also
+     * have a count of offloaded and pending flows on each of the netdevs
+     * that are in OOR state. Now rebalance each oor-netdev.
+     */
+    while (oor_netdev_count) {
+        struct netdev *netdev;
+        int offload_count;
+        int pending_count;
+        bool oor;
+
+        netdev = sort_flows[offload_index]->in_netdev;
+        ovs_assert(netdev_get_hw_info(netdev, HW_INFO_TYPE_OOR) == true);
+        VLOG_DBG("Offload rebalance: netdev: %s is OOR", netdev->name);
+
+        offload_count = netdev_get_hw_info(netdev, HW_INFO_TYPE_OFFL_COUNT);
+        pending_count = netdev_get_hw_info(netdev, HW_INFO_TYPE_PEND_COUNT);
+        pending_index = offload_index + offload_count;
+
+        oor = rebalance_device(udpif,
+                               &sort_flows[offload_index], offload_count,
+                               &sort_flows[pending_index], pending_count);
+        netdev_set_hw_info(netdev, HW_INFO_TYPE_OOR, oor);
+
+        offload_index = pending_index + pending_count;
+        netdev_set_hw_info(netdev, HW_INFO_TYPE_OFFL_COUNT, 0);
+        netdev_set_hw_info(netdev, HW_INFO_TYPE_PEND_COUNT, 0);
+        oor_netdev_count--;
+    }
+
+    for (int i = 0; i < total_flow_count; i++) {
+        struct udpif_key *ukey = sort_flows[i];
+        ukey_netdev_unref(ukey);
+    }
+    free(sort_flows);
+}
+
+static int
+udpif_flow_program(struct udpif *udpif, struct udpif_key *ukey,
+                   enum dpif_offload_type offload_type)
+{
+    struct dpif_op *opsp;
+    struct ukey_op uop;
+
+    opsp = &uop.dop;
+    put_op_init(&uop, ukey, DPIF_FP_CREATE);
+    dpif_operate(udpif->dpif, &opsp, 1, offload_type);
+
+    return opsp->error;
+}
+
+static int
+udpif_flow_unprogram(struct udpif *udpif, struct udpif_key *ukey,
+                     enum dpif_offload_type offload_type)
+{
+    struct dpif_op *opsp;
+    struct ukey_op uop;
+
+    opsp = &uop.dop;
+    delete_op_init(udpif, &uop, ukey);
+    dpif_operate(udpif->dpif, &opsp, 1, offload_type);
+
+    return opsp->error;
+}
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index f05f616fe..2bfe4ff24 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -519,6 +519,27 @@ 
         </p>
     </column>
 
+      <column name="other_config" key="offload-rebalance"
+              type='{"type": "boolean"}'>
+        <p>
+            Configures HW offload rebalancing, that allows to dynamically
+            offload and un-offload flows while an offload-device is out of
+            resources (OOR). This policy allows flows to be selected for
+            offloading based on the packets-per-second (pps) rate of flows.
+        </p>
+        <p>
+          Set this value to <code>true</code> to enable this option.
+        </p>
+        <p>
+          The default value is <code>false</code>. Changing this value requires
+          restarting the daemon.
+        </p>
+        <p>
+            This is only relevant if HW offloading is enabled (hw-offload).
+            When this policy is enabled, it also requires 'tc-policy' to
+            be set to 'skip_sw'.
+        </p>
+      </column>
     </group>
 
     <group title="Status">