diff --git a/include/dba.php b/include/dba.php
index 7d2d3bbd0f..8e2d18db60 100644
--- a/include/dba.php
+++ b/include/dba.php
@@ -138,6 +138,11 @@ class dba {
 		return $return;
 	}
 
+	/**
+	 * @brief Analyze a database query and log this if some conditions are met.
+	 *
+	 * @param string $query The database query that will be analyzed
+	 */
 	public function log_index($query) {
 		$a = get_app();
 
diff --git a/include/poller.php b/include/poller.php
index c0b92bb811..10bc70aae3 100644
--- a/include/poller.php
+++ b/include/poller.php
@@ -179,6 +179,8 @@ function poller_exec_function($queue, $funcname, $argv) {
 
 	$stamp = (float)microtime(true);
 
+	// We use the callstack here to analyze the performance of executed worker entries.
+	// For this reason the variables have to be initialized.
 	if (Config::get("system", "profiler")) {
 		$a->performance["start"] = microtime(true);
 		$a->performance["database"] = 0;
@@ -205,6 +207,7 @@ function poller_exec_function($queue, $funcname, $argv) {
 
 	logger("Process ".$mypid." - Prio ".$queue["priority"]." - ID ".$queue["id"].": ".$funcname." - done in ".$duration." seconds.");
 
+	// Write down the performance values into the log
 	if (Config::get("system", "profiler")) {
 		$duration = microtime(true)-$a->performance["start"];