conf: bg_workers auto-estimate function

src/knot/conf/conf.c

@@ -899,6 +899,16 @@ size_t conf_tcp_threads(const conf_t *conf)
 	return MAX(thrcount * 2, CONFIG_XFERS);
 }
 
+int conf_bg_threads(const conf_t *conf)
+{
+	if (conf->bg_workers < 1) {
+		return MIN(dt_optimal_size(), CONFIG_XFERS);
+	}
+
+	return conf->bg_workers;
+}
+
+
 void conf_init_zone(conf_zone_t *zone)
 {
 	if (!zone) {

src/knot/conf/conf.h

@@ -412,6 +412,9 @@ size_t conf_udp_threads(const conf_t *conf);
 /*! \brief Return the number of TCP threads according to the configuration. */
 size_t conf_tcp_threads(const conf_t *conf);
 
+/*! \brief Return the number of background worker threads. */
+int conf_bg_threads(const conf_t *conf);
+
 /* \brief Initialize zone config. */
 void conf_init_zone(conf_zone_t *zone);
 

src/knot/main.c

@@ -279,7 +279,7 @@ int main(int argc, char **argv)
 
 	/* Initialize server. */
 	server_t server;
-	res = server_init(&server, config->bg_workers);
+	res = server_init(&server, conf_bg_threads(config));
 	if (res != KNOT_EOK) {
 		log_server_fatal("Could not initialize server: %s\n",
 		                 knot_strerror(res));

src/knot/server/server.c

@@ -291,12 +291,6 @@ int server_init(server_t *server, int bg_workers)
 		return KNOT_ENOMEM;
 	}
 
-	/* Create zone events threads. */
-	if (bg_workers < 1) {
-		bg_workers = dt_optimal_size();
-	}
-	assert(bg_workers > 0);
-
 	server->workers = worker_pool_create(bg_workers);
 	if (server->workers == NULL) {
 		dt_delete(&server->iosched);