[buffermgr] Support maximum port headroom checking (sonic-net#1607)

* Support maximum port headroom checking

- Fetch the maximum port headroom via fetching the port attribute SAI_PORT_ATTR_QOS_MAXIMUM_HEADROOM_SIZE when the orchagent starts and push the data into STATE_DB
- Check the accumulative port headroom against the maximum headroom in buffer_check_headroom_<vendor>.lua

On Mellanox platform, this PR depends on PR sonic-net#6566 to be merged. In that PR the required SAI attribute is supported.
On other platforms, there is no dependency.

Signed-off-by: Stephen Sun stephens@nvidia.com

Why I did it
On some platforms, the SAI will notify orchagent shut down if a headroom size that causes the accumulative port headroom to exceed its limit is programmed to SAI.
To avoid that, we need to check this before programming it to SAI.

How I verified it
Run the regression test.

cfgmgr/buffer_check_headroom_mellanox.lua

@@ -10,36 +10,15 @@ local new_pg = ARGV[3]
 local accumulative_size = 0
 
 local appl_db = "0"
-local config_db = "4"
 local state_db = "6"
 
 local ret_true = {}
-local ret_false = {}
 local ret = {}
 local default_ret = {}
 
 table.insert(ret_true, "result:true")
-table.insert(ret_false, "result:false")
 
--- Fetch the cable length from CONFIG_DB
-redis.call('SELECT', config_db)
-local cable_length_keys = redis.call('KEYS', 'CABLE_LENGTH*')
-if #cable_length_keys == 0 then
-    return ret_true
-end
-
--- Check whether cable length exceeds 300m (maximum value in the non-dynamic-buffer solution)
-local cable_length_str = redis.call('HGET', cable_length_keys[1], port)
-if cable_length_str == nil then
-    return ret_true
-end
-local cable_length = tonumber(string.sub(cable_length_str, 1, -2))
-if cable_length > 300 then
-    default_ret = ret_false
-else
-    default_ret = ret_true
-end
-table.insert(default_ret, 'debug:no max_headroom_size configured, check cable length instead')
+default_ret = ret_true
 
 local speed = redis.call('HGET', 'PORT|' .. port, 'speed')
 
@@ -67,7 +46,6 @@ local function get_number_of_pgs(keyname)
     local range = string.match(keyname, "Ethernet%d+:([^%s]+)$")
     local size
     if range == nil then
-        table.insert(debuginfo, "debug:invalid pg:" .. keyname)
         return 0
     end
     if string.len(range) == 1 then
@@ -119,11 +97,9 @@ if max_headroom_size > accumulative_size then
     table.insert(ret, "result:true")
 else
     table.insert(ret, "result:false")
+    table.insert(ret, "debug:Accumulative headroom on port " .. accumulative_size .. " exceeds the maximum available headroom which is " .. max_headroom_size)
 end
 
-table.insert(ret, "debug:max headroom:" .. max_headroom_size)
-table.insert(ret, "debug:accumulative headroom:" .. accumulative_size)
-
 for i = 1, #debuginfo do
     table.insert(ret, debuginfo[i])
 end

orchagent/port.h

@@ -124,6 +124,7 @@ class Port
     uint32_t  m_vnid = VNID_NONE;
     uint32_t  m_fdb_count = 0;
     uint32_t  m_up_member_count = 0;
+    uint32_t  m_maximum_headroom = 0;
 
     /*
      * Following two bit vectors are used to lock

orchagent/portsorch.cpp

@@ -257,6 +257,9 @@ PortsOrch::PortsOrch(DBConnector *db, vector<table_name_with_pri_t> &tableNames)
     m_flexCounterTable = unique_ptr<ProducerTable>(new ProducerTable(m_flex_db.get(), FLEX_COUNTER_TABLE));
     m_flexCounterGroupTable = unique_ptr<ProducerTable>(new ProducerTable(m_flex_db.get(), FLEX_COUNTER_GROUP_TABLE));
 
+    m_state_db = shared_ptr<DBConnector>(new DBConnector("STATE_DB", 0));
+    m_stateBufferMaximumValueTable = unique_ptr<Table>(new Table(m_state_db.get(), STATE_BUFFER_MAXIMUM_VALUE_TABLE));
+
     initGearbox();
 
     string queueWmSha, pgWmSha;
@@ -3291,6 +3294,25 @@ void PortsOrch::initializePriorityGroups(Port &port)
     SWSS_LOG_INFO("Get priority groups for port %s", port.m_alias.c_str());
 }
 
+void PortsOrch::initializePortMaximumHeadroom(Port &port)
+{
+    sai_attribute_t attr;
+
+    attr.id = SAI_PORT_ATTR_QOS_MAXIMUM_HEADROOM_SIZE;
+
+    sai_status_t status = sai_port_api->get_port_attribute(port.m_port_id, 1, &attr);
+    if (status != SAI_STATUS_SUCCESS)
+    {
+        SWSS_LOG_NOTICE("Unable to get the maximum headroom for port %s rv:%d, ignored", port.m_alias.c_str(), status);
+        return;
+    }
+
+    vector<FieldValueTuple> fvVector;
+    port.m_maximum_headroom = attr.value.u32;
+    fvVector.emplace_back("max_headroom_size", to_string(port.m_maximum_headroom));
+    m_stateBufferMaximumValueTable->set(port.m_alias, fvVector);
+}
+
 bool PortsOrch::initializePort(Port &port)
 {
     SWSS_LOG_ENTER();
@@ -3299,6 +3321,7 @@ bool PortsOrch::initializePort(Port &port)
 
     initializePriorityGroups(port);
     initializeQueues(port);
+    initializePortMaximumHeadroom(port);
 
     /* Create host interface */
     if (!addHostIntfs(port, port.m_alias, port.m_hif_id))

orchagent/portsorch.h

@@ -155,6 +155,7 @@ class PortsOrch : public Orch, public Subject
     unique_ptr<Table> m_pgTable;
     unique_ptr<Table> m_pgPortTable;
     unique_ptr<Table> m_pgIndexTable;
+    unique_ptr<Table> m_stateBufferMaximumValueTable;
     unique_ptr<ProducerTable> m_flexCounterTable;
     unique_ptr<ProducerTable> m_flexCounterGroupTable;
 
@@ -164,6 +165,7 @@ class PortsOrch : public Orch, public Subject
 
     shared_ptr<DBConnector> m_counter_db;
     shared_ptr<DBConnector> m_flex_db;
+    shared_ptr<DBConnector> m_state_db;
 
     FlexCounterManager port_stat_manager;
     FlexCounterManager port_buffer_drop_stat_manager;
@@ -226,6 +228,7 @@ class PortsOrch : public Orch, public Subject
 
     bool initializePort(Port &port);
     void initializePriorityGroups(Port &port);
+    void initializePortMaximumHeadroom(Port &port);
     void initializeQueues(Port &port);
 
     bool addHostIntfs(Port &port, string alias, sai_object_id_t &host_intfs_id);