T7757: VPP add auto calculation of buffer-per-numa parameter as default

4 files changed, 51 insertions, 16 deletions

diff --git a/interface-definitions/vpp.xml.in b/interface-definitions/vpp.xml.in
index 356345f84..e7a21ecf1 100644
--- a/interface-definitions/vpp.xml.in
+++ b/interface-definitions/vpp.xml.in
@@ -360,14 +360,19 @@
                 <properties>
                   <help>Number of buffers per numa node</help>
                   <valueHelp>
-                    <format>u32:0-4294967295</format>
+                    <format>u32:16384-4294967295</format>
                     <description>Number of buffers</description>
                   </valueHelp>
+                  <valueHelp>
+                     <format>auto</format>
+                     <description>Auto calculate number of buffers per numa node</description>
+                   </valueHelp>
                   <constraint>
-                    <validator name="numeric" argument="--range 0-4294967295"/>
+                    <validator name="numeric" argument="--range 16384-4294967295"/>
+                    <regex>(auto)</regex>
                   </constraint>
                 </properties>
-                <defaultValue>16384</defaultValue>
+                <defaultValue>auto</defaultValue>
               </leafNode>
               <leafNode name="data-size">
                 <properties>
diff --git a/python/vyos/vpp/config_resource_checks/memory.py b/python/vyos/vpp/config_resource_checks/memory.py
index 8b201ef87..ea4697ba2 100644
--- a/python/vyos/vpp/config_resource_checks/memory.py
+++ b/python/vyos/vpp/config_resource_checks/memory.py
@@ -199,11 +199,18 @@ def buffers_required(settings: dict, workers) -> int:
     """
     buffers_total = 0
     for ifname, iface_config in settings.get('interface', {}).items():
+        # Do not include XDP interfaces in buffer calculations.
+        # Unlike DPDK, XDP does not use VPP-managed mbufs for RX/TX rings,
+        # so buffer requirements cannot be derived from descriptors here.
+        # Buffers for XDP are handled internally by the kernel/XDP layer,
+        # not by VPP’s buffer allocator.
         if iface_config.get('driver') == 'xdp':
             continue
         dpdk_options = iface_config.get('dpdk_options', {})
         rx_queues = int(dpdk_options.get('num_rx_queues', 1))
         rx_desc = int(dpdk_options.get('num_rx_desc'))
+        # default TX queues is equal to number of worker threads
+        # plus 1 main thread
         tx_queues = int(dpdk_options.get('num_tx_queues', workers + 1))
         tx_desc = int(dpdk_options.get('num_tx_desc'))
 
diff --git a/python/vyos/vpp/config_verify.py b/python/vyos/vpp/config_verify.py
index 78c5d420b..71cf97423 100644
--- a/python/vyos/vpp/config_verify.py
+++ b/python/vyos/vpp/config_verify.py
@@ -317,7 +317,7 @@ def verify_vpp_cpu_main_core(cpu_settings: dict) -> None:
         )
 
 
-def verify_vpp_settings_cpu_workers(cpu_settings: dict) -> int:
+def verify_vpp_settings_cpu_workers(cpu_settings: dict):
     """
     Verify that the system has enough available CPU cores
     to run a given amount of worker processes (1 worker/core)
@@ -331,10 +331,8 @@ def verify_vpp_settings_cpu_workers(cpu_settings: dict) -> int:
             f'(reduce to {available_cores} or less)'
         )
 
-    return workers
 
-
-def verify_vpp_settings_cpu_corelist_workers(cpu_settings: dict) -> int:
+def verify_vpp_settings_cpu_corelist_workers(cpu_settings: dict):
     """
     Verify that the CPU cores provided to the config are free and can be used by VPP
     """
@@ -366,8 +364,6 @@ def verify_vpp_settings_cpu_corelist_workers(cpu_settings: dict) -> int:
     if len(all_core_nums) > cpu_checks.available_cores_count(cpu_settings):
         raise ConfigError(f'{error_msg}: Not enough free CPUs in the system.')
 
-    return len(all_core_nums)
-
 
 def verify_vpp_nat44_workers(workers: int, nat44_workers: list):
     if workers < 1:
diff --git a/src/conf_mode/vpp.py b/src/conf_mode/vpp.py
index b205291f2..518860605 100755
--- a/src/conf_mode/vpp.py
+++ b/src/conf_mode/vpp.py
@@ -60,6 +60,7 @@ from vyos.vpp.config_verify import (
     verify_vpp_main_heap_size,
     verify_vpp_buffers,
 )
+from vyos.vpp.config_resource_checks import memory
 from vyos.vpp.config_filter import iface_filter_eth
 from vyos.vpp.utils import EthtoolGDrvinfo
 from vyos.vpp.configdb import JSONStorage
@@ -148,6 +149,28 @@ def _unload_module(module_name: str):
         raise
 
 
+def _get_workers_count(cpu_settings: dict) -> int:
+    if 'corelist_workers' in cpu_settings:
+        corelist_workers = []
+        for worker_range in cpu_settings['corelist_workers']:
+            core_numbers = worker_range.split('-')
+            corelist_workers.extend(
+                range(int(core_numbers[0]), int(core_numbers[-1]) + 1)
+            )
+
+        return len(corelist_workers)
+
+    return int(cpu_settings.get('workers', 0))
+
+
+def _normalize_buffers(config: dict):
+    """Replace 'auto' buffers_per_numa with calculated value"""
+    if config['settings']['buffers']['buffers_per_numa'] == 'auto':
+        workers = _get_workers_count(config['settings'].get('cpu', {}))
+        buffers = memory.buffers_required(config['settings'], workers)
+        config['settings']['buffers']['buffers_per_numa'] = str(buffers)
+
+
 def get_config(config=None):
     # use persistent config to store interfaces data between executions
     # this is required because some interfaces after they are connected
@@ -242,9 +265,10 @@ def get_config(config=None):
         default_values_effective = conf.get_config_defaults(
             **effective_config.kwargs, recursive=True
         )
-        config['effective'] = config_dict_merge(
-            default_values_effective, effective_config
-        )
+        effective_config = config_dict_merge(default_values_effective, effective_config)
+        # Buffer normalization (auto → computed)
+        _normalize_buffers(effective_config)
+        config['effective'] = effective_config
 
     if 'settings' in config:
         if 'interface' in config['settings']:
@@ -317,6 +341,9 @@ def get_config(config=None):
                         xdp_api_params['flags'] = 'no_syscall_lock'
                     iface_config['xdp_api_params'] = xdp_api_params
 
+        # Buffer normalization (auto → computed)
+        _normalize_buffers(config)
+
     if removed_ifaces:
         config['removed_ifaces'] = removed_ifaces
         config['xconn_members'] = xconn_members
@@ -373,8 +400,6 @@ def verify(config):
             raise ConfigError(f'Interface {iface} does not exist or is not Ethernet!')
 
     # Resource usage checks
-    workers = 0
-
     if 'cpu' in config['settings']:
         cpu_settings = config['settings']['cpu']
 
@@ -388,14 +413,16 @@ def verify(config):
 
         # Check if there are enough CPU cores to add workers
         if 'workers' in cpu_settings:
-            workers = verify_vpp_settings_cpu_workers(cpu_settings)
+            verify_vpp_settings_cpu_workers(cpu_settings)
 
         if 'main_core' in cpu_settings:
             verify_vpp_cpu_main_core(cpu_settings)
 
         # Check the CPU main core not falling to the corelist-workers
         if 'corelist_workers' in cpu_settings:
-            workers = verify_vpp_settings_cpu_corelist_workers(cpu_settings)
+            verify_vpp_settings_cpu_corelist_workers(cpu_settings)
+
+    workers = _get_workers_count(config['settings'].get('cpu', {}))
 
     if 'workers' in config['settings']['nat44']:
         verify_vpp_nat44_workers(