bgwriterLruMultiplier

The average recent need for new buffers is multiplied by bgwriter_lru_multiplier to arrive at an estimate of the number that will be needed during the next round, (up to bgwriter_lru_maxpages). 1.0 represents a “just in time” policy of writing exactly the number of buffers predicted to be needed. Larger values provide some cushion against spikes in demand, while smaller values intentionally leave writes to be done by server processes. The default is 2.0.