fix: Fixed the default fping config + changed variable name (#8060)

* fix: Fixed the default fping config and added docs on caveats to changing timeout

* millisec -> interval

* removed retries config option, no needed

* Update Performance.md

doc/Support/Configuration.md

@@ -68,20 +68,28 @@ Please see [1 Minute polling](1-Minute-Polling.md) for information on configurin
 ```php
 $config['fping']            = "/usr/bin/fping";
 $config['fping6']           = "fping6";
-$config['fping_options']['retries'] = 3;
 $config['fping_options']['timeout'] = 500;
 $config['fping_options']['count'] = 3;
-$config['fping_options']['millisec'] = 200;
+$config['fping_options']['interval'] = 500;
 ```
 `fping` configuration options:
 
-* `retries` (`fping` parameter `-r`): Number of times an attempt at pinging a target will be made, not including the first try.
-* `timeout` (`fping` parameter `-t`): Amount of time that fping waits for a response to its first request (in milliseconds).
+* `timeout` (`fping` parameter `-t`): Amount of time that fping waits for a response to its first request (in milliseconds). **See note below**
 * `count` (`fping` parameter `-c`): Number of request packets to send to each target.
-* `millisec` (`fping` parameter `-p`): Time in milliseconds that fping waits between successive packets to an individual target.
+* `interval` (`fping` parameter `-p`): Time in milliseconds that fping waits between successive packets to an individual target.
+
+> NOTE: Setting a higher timeout value than the interval value can lead to slowing down poller. Example:
+>
+> timeout: 3000
+>
+> count: 3
+>
+> interval: 500
+>
+> In this example, interval will be overwritten by the timeout value of 3000 which is 3 seconds. As we send three icmp packets (count: 3), each one is delayed by 3 seconds which will result in fping taking > 6 seconds to return results.
 
 You can disable the fping / icmp check that is done for a device to be determined to be up on a global or per device basis.
-**We don't advice disabling the fping / icmp check unless you know the impact, at worst if you have a large number of devices down
+**We don't advise disabling the fping / icmp check unless you know the impact, at worst if you have a large number of devices down
 then it's possible that the poller would no longer complete in 5 minutes due to waiting for snmp to timeout.**
 
 Globally disable fping / icmp check:

doc/Support/Performance.md

@@ -60,6 +60,29 @@ You can also set this globally with the config option `$config['snmp']['max_oid'
 
 > NOTE: It is advisable to monitor sensor polling when you change this to ensure you don't set the value too high.
 
+### fping tuning
+
+You can change some of the default fping options used globally or per device. The defaults are:
+
+```php
+$config['fping_options']['timeout'] = 500;
+$config['fping_options']['count']   = 3;
+$config['fping_options']['interval'] = 500;
+```
+
+If your devices are slow to respond then you will need to increase the timeout value and potentially the interval value.
+However if your network is stable, you can increase poller performance by dropping the count value to 1 and/or the timeout+millsec value to 200 or 300:
+
+```php
+$config['fping_options']['timeout'] = 300;
+$config['fping_options']['count']   = 1;
+$config['fping_options']['interval'] = 300;
+```
+
+This will mean that we no longer delay each icmp packet sent (we send 3 in total by default) by 0.5 seconds. With only 1 icmp packet
+being sent then we will receive a response quicker. The defaults mean it will take at least 1 second for a response no matter how 
+quick the icmp packet is returned.
+
 ### Optimise poller-wrapper
 
 The default 16 threads that `poller-wrapper.py` runs as isn't necessarily the optimal number. A general rule of thumb is 

includes/defaults.inc.php

@@ -44,10 +44,10 @@ $config['own_hostname'] = 'localhost';
 // Location of executables
 //$config['fping']                    = '/usr/sbin/fping';
 //$config['fping6']                   = '/usr/sbin/fping6';
-$config['fping_options']['retries'] = 3;
+// https://docs.librenms.org/Support/Configuration/#fping
 $config['fping_options']['timeout'] = 500;
 $config['fping_options']['count']   = 3;
-$config['fping_options']['millisec'] = 200;
+$config['fping_options']['interval'] = 500;
 $config['snmpwalk']                  = '/usr/bin/snmpwalk';
 $config['snmpget']                   = '/usr/bin/snmpget';
 $config['snmpbulkwalk']              = '/usr/bin/snmpbulkwalk';

includes/functions.php

@@ -657,29 +657,23 @@ function isPingable($hostname, $address_family = AF_INET, $attribs = array())
     $response = array();
     if (can_ping_device($attribs) === true) {
         $fping_params = '';
-        if (is_numeric($config['fping_options']['retries']) && $config['fping_options']['retries'] > 0) {
-            if ($config['fping_options']['retries'] > 20) {
-                $config['fping_options']['retries'] = 20;
-            }
-            $fping_params .= ' -r ' . $config['fping_options']['retries'];
-        }
         if (is_numeric($config['fping_options']['timeout'])) {
             if ($config['fping_options']['timeout'] < 50) {
                 $config['fping_options']['timeout'] = 50;
             }
-            if ($config['fping_options']['millisec'] < $config['fping_options']['timeout']) {
-                $config['fping_options']['millisec'] = $config['fping_options']['timeout'];
+            if ($config['fping_options']['interval'] < $config['fping_options']['timeout']) {
+                $config['fping_options']['interval'] = $config['fping_options']['timeout'];
             }
             $fping_params .= ' -t ' . $config['fping_options']['timeout'];
         }
         if (is_numeric($config['fping_options']['count']) && $config['fping_options']['count'] > 0) {
             $fping_params .= ' -c ' . $config['fping_options']['count'];
         }
-        if (is_numeric($config['fping_options']['millisec'])) {
-            if ($config['fping_options']['millisec'] < 20) {
-                $config['fping_options']['millisec'] = 20;
+        if (is_numeric($config['fping_options']['interval'])) {
+            if ($config['fping_options']['interval'] < 20) {
+                $config['fping_options']['interval'] = 20;
             }
-            $fping_params .= ' -p ' . $config['fping_options']['millisec'];
+            $fping_params .= ' -p ' . $config['fping_options']['interval'];
         }
         $status = fping($hostname, $fping_params, $address_family);
         if ($status['exitcode'] > 0 || $status['loss'] == 100) {

includes/process_config.inc.php

@@ -45,6 +45,10 @@ if ($config['rrdgraph_real_95th']) {
     $config['rrdgraph_real_percentile'] = $config['rrdgraph_real_95th'];
 }
 
+if (isset($config['fping_options']['millisec']) && is_numeric($config['fping_options']['millisec'])) {
+    $config['fping_options']['interval'] = $config['fping_options']['millisec'];
+}
+
 // make sure we have full path to binaries in case PATH isn't set
 foreach (array('fping', 'fping6', 'snmpgetnext') as $bin) {
     if (!is_executable(Config::get($bin))) {