T7348: Add config CPU thread-count for accel-ppp services

Accel-ppp services should not use all CPU cores to process requests.
At the moment accel-ppp services use all available CPU cores
to process requests from the subscribers (establish/update session/etc).
During mass connection of sessions, this can lead to the fact that it
utilizes all CPU, and for other services like FRR, there is not enough
CPU time to process their own stable work.

services:
 - L2TP
 - SSTP
 - PPPoE
 - IPoE
 - PPtP

Add this option configurable and use all cores if not set:

```
set service pppoe-server thread-count < all | half | x >
```
The defaultValue `all`

2 files changed, 17 insertions, 1 deletions

diff --git a/python/vyos/configdict.py b/python/vyos/configdict.py
index ff0a15933..a34b0176a 100644
--- a/python/vyos/configdict.py
+++ b/python/vyos/configdict.py
@@ -661,6 +661,7 @@ def get_accel_dict(config, base, chap_secrets, with_pki=False):
     Return a dictionary with the necessary interface config keys.
     """
     from vyos.utils.cpu import get_core_count
+    from vyos.utils.cpu import get_half_cpus
     from vyos.template import is_ipv4
 
     dict = config.get_config_dict(base, key_mangling=('-', '_'),
@@ -670,7 +671,16 @@ def get_accel_dict(config, base, chap_secrets, with_pki=False):
                                   with_pki=with_pki)
 
     # set CPUs cores to process requests
-    dict.update({'thread_count' : get_core_count()})
+    match dict.get('thread_count'):
+        case 'all':
+            dict['thread_count'] = get_core_count()
+        case 'half':
+            dict['thread_count'] = get_half_cpus()
+        case str(x) if x.isdigit():
+            dict['thread_count'] = int(x)
+        case _:
+            dict['thread_count'] = get_core_count()
+
     # we need to store the path to the secrets file
     dict.update({'chap_secrets_file' : chap_secrets})
 
diff --git a/python/vyos/utils/cpu.py b/python/vyos/utils/cpu.py
index 8ace77d15..6f21eb526 100644
--- a/python/vyos/utils/cpu.py
+++ b/python/vyos/utils/cpu.py
@@ -26,6 +26,7 @@ It has special cases for x86_64 and MAY work correctly on other architectures,
 but nothing is certain.
 """
 
+import os
 import re
 
 def _read_cpuinfo():
@@ -114,3 +115,8 @@ def get_available_cpus():
     out = json.loads(cmd('lscpu --extended -b --json'))
 
     return out['cpus']
+
+
+def get_half_cpus():
+    """ return 1/2 of the numbers of available CPUs """
+    return max(1, os.cpu_count() // 2)