From 06e9c81bd078b14dfc7d728b027fe42e5dc4755c Mon Sep 17 00:00:00 2001 From: Christopher Faulet Date: Tue, 16 May 2023 18:28:57 +0200 Subject: [PATCH] MEDIUM: resolvers: Stop scheduling resolution during stopping stage When the process is stopping, the server resolutions are suspended. However the task is still periodically woken up for nothing. If there is a huge number of resolution, it may lead to a noticeable CPU consumption for no reason. To avoid this extra CPU cost, we stop to schedule the the resolution tasks during the stopping stage. Of course, it is only true for server resolutinos. Dynamic ones, via do-resolve actions, are not concerned. These ones must still be triggered during stopping stage. Concretly, during the stopping stage, the resolvers task is no longer scheduled if there is no running resolutions. In this case, if a do-resolve action is evaluated, the task is woken up. This patch should partially solve the issue #2145. --- src/resolvers.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/resolvers.c b/src/resolvers.c index add9a25ab..c820d9cfb 100644 --- a/src/resolvers.c +++ b/src/resolvers.c @@ -459,7 +459,7 @@ void resolv_trigger_resolution(struct resolv_requester *req) /* The resolution must not be triggered yet. Use the cached response, if * valid */ exp = tick_add(res->last_resolution, resolvers->hold.valid); - if (resolvers->t && (res->status != RSLV_STATUS_VALID || + if (resolvers->t && (!tick_isset(resolvers->t->expire) || res->status != RSLV_STATUS_VALID || !tick_isset(res->last_resolution) || tick_is_expired(exp, now_ms))) { /* If the resolution is not running and the requester is a * server, reset the resolution timer to force a quick @@ -2457,6 +2457,9 @@ struct task *process_resolvers(struct task *t, void *context, unsigned int state if (unlikely(stopping)) { struct dns_nameserver *ns; + if (LIST_ISEMPTY(&resolvers->resolutions.curr)) + t->expire = TICK_ETERNITY; + list_for_each_entry(ns, &resolvers->nameservers, list) { if (ns->stream) task_wakeup(ns->stream->task_idle, TASK_WOKEN_MSG);