static unsigned burst_modulate(unsigned burst, uint64_t available) {
        unsigned k;

        /* Modulates the burst rate a bit with the amount of available
         * disk space */

        k = log2u64(available);

        /* 1MB */
        if (k <= 20)
                return burst;

        burst = (burst * (k-16)) / 4;
…
int journal_ratelimit_test(
                OrderedHashmap **groups_by_id,
                const char *id,
                usec_t rl_interval,
                unsigned rl_burst,
                int priority,
                uint64_t available) {
…
        if (rl_interval == 0 || rl_burst == 0)
                return 1;

        burst = burst_modulate(rl_burst, available);

        p = &g->pools[priority_map[priority]];

        if (p->begin <= 0) {
                p->suppressed = 0;
                p->num = 1;
                p->begin = ts;
                return 1;
        }

        if (usec_add(p->begin, rl_interval) < ts) {
                unsigned s;

                s = p->suppressed;
                p->suppressed = 0;
                p->num = 1;
                p->begin = ts;

                return 1 + s;
        }

        if (p->num < burst) {
                p->num++;
                return 1;
        }

        p->suppressed++;
        return 0;
}

Warm-up