zone: optimize memory trimming frequency for many zones (server start)

diff --git a/src/knot/updates/zone-update.c b/src/knot/updates/zone-update.c
index 1e2b8ab2dc09d071650761da3681869cdfafa71b..c9ba288f03a697c2afc0141e27333c12bff07135 100644 (file)
--- a/src/knot/updates/zone-update.c
+++ b/src/knot/updates/zone-update.c
@@ -870,24 +870,6 @@ static int update_catalog(conf_t *conf, zone_update_t *update)
        return ret;
 }
 
-typedef struct {
-       pthread_mutex_t lock;
-       size_t counter;
-} counter_reach_t;
-
-static bool counter_reach(counter_reach_t *counter, size_t increment, size_t limit)
-{
-       bool reach = false;
-       pthread_mutex_lock(&counter->lock);
-       counter->counter += increment;
-       if (counter->counter >= limit) {
-               counter->counter = 0;
-               reach = true;
-       }
-       pthread_mutex_unlock(&counter->lock);
-       return reach;
-}
-
 /*! \brief Struct for what needs to be cleared after RCU.
  *
  * This can't be zone_update_t structure as this might be already freed at that time.
@@ -904,12 +886,38 @@ typedef struct {
        size_t new_cont_size;
 } update_clear_ctx_t;
 
+static void call_mem_trim(update_clear_ctx_t *ctx)
+{
+       static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+       static bool running = false;
+       static size_t counter = 0;
+       static knot_millis_t next = 0;
+
+       knot_millis_t now = knot_millis_now();
+       pthread_mutex_lock(&lock);
+       counter += ctx->new_cont_size;
+       if (running || counter < UPDATE_MEMTRIM_AT || now < next) {
+               pthread_mutex_unlock(&lock);
+               return;
+       }
+       running = true;
+       pthread_mutex_unlock(&lock);
+
+       mem_trim();
+       knot_millis_t diff = knot_millis_now() - now;
+
+       pthread_mutex_lock(&lock);
+       running = false;
+       counter = 0;
+       next = now + 2 * diff;
+       pthread_mutex_unlock(&lock);
+}
+
 static void *update_clear_retry(void *arg);
 
 static void update_clear(struct rcu_head *param)
 {
-       static counter_reach_t counter = { PTHREAD_MUTEX_INITIALIZER, 0 };
-
        update_clear_ctx_t *ctx = (update_clear_ctx_t *)param;
 
        if (ctx->free_contents != NULL) {
@@ -929,9 +937,7 @@ static void update_clear(struct rcu_head *param)
        apply_cleanup(ctx->cleanup_apply);
        free(ctx->cleanup_apply);
 
-       if (counter_reach(&counter, ctx->new_cont_size, UPDATE_MEMTRIM_AT)) {
-               mem_trim();
-       }
+       call_mem_trim(ctx);
 
        free(ctx);
 }